[MNT] new CI workflow to test extras (#5375)

new CI workflow that tris to install `sktime` each extra to see if the
specified packages (with specified versions or versions bounds) are
compatible with one another.

when does it run:

1. runs first of every month at 00:00
2. runs for a PR into `main`that modifies `pyproject.toml`
3. runs when triggered manually

what does it do:

1. runs for all supported operating system
2. runs for all supported python version
3. runs for all supported extras
4. creates a new python environment of specific python version on a
specific operating system with a specific python version and installs
`sktime` with a specific extra

what does it not do:

1. installation multiple extras simultaneously - too many combinations
2. automated resolution if installation fails with conflicts - probably
impossible

other changes

1. formatted of `pyproject.toml` with `pyproject-fmt` as needed to test
workflow
2. skipped `mrsqm` from `classification` extra as it was failing to be
built in most combinations
3. added python version bound for relevant packages

.github/actions/validate-extra/action.yml

@@ -0,0 +1,21 @@
+name: test specific sktime extra
+description: install individual extra of sktime
+inputs:
+  sktime-extra-identifier:
+    description: name of sktime extra
+    required: true
+  python-version-identifier:
+    description: python version to run tests
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: repository checkout step
+      uses: actions/checkout@v4
+    - name: python environment step
+      uses: actions/setup-python@v4
+      with:
+        python-version: ${{ inputs.python-version-identifier }}
+    - name: extra installation step
+      run: python3 -m pip install .[${{ inputs.sktime-extra-identifier }}]
+      shell: bash

.github/workflows/validate_extras.yml

@@ -0,0 +1,45 @@
+name: extras validation
+on:
+  pull_request:
+    branches:
+      - main
+    paths:
+      - pyproject.toml
+  schedule:
+    - cron: 0 0 1 * *
+  workflow_dispatch:
+jobs:
+  test_installations:
+    name: extras installation
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version:
+          - "3.8"
+          - "3.9"
+          - "3.10"
+          - "3.11"
+          - "3.12"
+        operating-system:
+          - macos-latest
+          - ubuntu-latest
+          - windows-latest
+        sktime-extra:
+          - alignment
+          - annotation
+          - classification
+          - clustering
+          - forecasting
+          - networks
+          - param_est
+          - regression
+          - transformations
+    runs-on: ${{ matrix.operating-system }}
+    steps:
+      - name: checkout pull request branch
+        uses: actions/checkout@v4
+      - name: install ${{ matrix.sktime-extra }} extra on python ${{ matrix.python-version }}
+        uses: ./.github/actions/validate-extra
+        with:
+          sktime-extra-identifier: ${{ matrix.sktime-extra }}
+          python-version-identifier: ${{ matrix.python-version }}

pyproject.toml

@@ -133,22 +133,21 @@ all_extras_pandas2 = [
 annotation = [
   "hmmlearn<0.4,>=0.2.7",
   'numba<0.59,>=0.53; python_version < "3.12"',
-  "pyod<1.2,>=0.8",
+  'pyod<1.2,>=0.8; python_version < "3.12"',
 ]
 binder = [
   "jupyter",
   "pandas<2.0.0",
 ]
 classification = [
-  "esig<0.10,>=0.9.7",
-  "mrsqm<0.1,>=0.0.3",
+  'esig<0.10,>=0.9.7; python_version < "3.11"',
   'numba<0.59,>=0.53; python_version < "3.12"',
-  "tensorflow<=2.14,>=2",
+  'tensorflow<=2.14,>=2; python_version < "3.12"',
   'tsfresh<0.21,>=0.17; python_version < "3.12"',
 ]
 clustering = [
   'numba<0.59,>=0.53; python_version < "3.12"',
-  "tslearn<0.6.3,>=0.5.2",
+  'tslearn<0.6.3,>=0.5.2; python_version < "3.12"',
 ]
 cython_extras = [
   "mrseql",
@@ -184,11 +183,11 @@ docs = [
   "tabulate",
 ]
 forecasting = [
-  "arch<6.3.0,>=5.6",
+  "arch<6.3,>=5.6",
   'pmdarima!=1.8.1,<2.1,>=1.8; python_version < "3.12"',
-  'prophet<1.2,>=1.1; python_version < "3.12"',
-  "skpro<2.2.0,>=2",
-  'statsforecast<1.7.0,>=0.5.2; python_version < "3.12"',
+  "prophet<1.2,>=1.1",
+  "skpro<2.2,>=2",
+  'statsforecast<1.7,>=0.5.2; python_version < "3.12"',
   "statsmodels<0.15,>=0.12.1",
   'tbats<1.2,>=1.1; python_version < "3.12"',
 ]
@@ -203,7 +202,7 @@ mlflow_tests = [
 ]
 networks = [
   "keras-self-attention<0.52,>=0.51",
-  "tensorflow<=2.14,>=2",
+  'tensorflow<=2.14,>=2; python_version < "3.12"',
 ]
 pandas1 = [
   "pandas<2.0.0",
@@ -214,10 +213,10 @@ param_est = [
 ]
 regression = [
   'numba<0.59,>=0.53; python_version < "3.12"',
-  "tensorflow<=2.14,>=2",
+  'tensorflow<=2.14,>=2; python_version < "3.12"',
 ]
 transformations = [
-  "esig<0.10,>=0.9.7",
+  'esig<0.10,>=0.9.7; python_version < "3.11"',
   "filterpy<1.5,>=1.4.5",
   "holidays<0.35,>=0.29",
   "mne<1.6,>=1.5",