Make 3.12 default (#68)

* Make 3.12 default

* Try setting version explicitly

.github/CONTRIBUTING.md

@@ -35,12 +35,12 @@ You can (and should) run our test suite using [Nox].
 However, you’ll probably want a more traditional environment as well.
 
 First, create a [virtual environment](https://virtualenv.pypa.io/) so you don't break your system-wide Python installation.
-We recommend using the Python version from the `.python-version` file in project's root directory.
+We recommend using the Python version from the `.python-version-default` file in project's root directory.
 
 If you're using [*direnv*](https://direnv.net), you can automate the creation of a virtual environment with the correct Python version by adding the following `.envrc` to the project root after cloning it:
 
 ```bash
-layout python python$(cat .python-version)
+layout python python$(cat .python-version-default)
 ```
 
 [Create a fork](https://github.com/hynek/environ-config/fork) of the repository and clone it:

.github/workflows/ci.yml

@@ -5,7 +5,6 @@ on:
   push:
     branches: [main]
   pull_request:
-    branches: [main]
   workflow_dispatch:
 
 env:
@@ -30,6 +29,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           cache: pip
+          python-version: "3.x"
 
       - run: python -Im pip install --upgrade wheel nox
 
@@ -43,6 +43,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
         with:
+          python-version-file: .python-version-default
           cache: pip
       - run: python -Im pip install build
 
@@ -114,6 +115,7 @@ jobs:
           workflow-artifact-name: ${{ env.sdist-artifact }}
       - uses: actions/setup-python@v4
         with:
+          python-version-file: .python-version-default
           cache: pip
 
       - run: python -Im pip install --upgrade coverage[toml]
@@ -212,6 +214,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
         with:
+          python-version-file: .python-version-default
           cache: pip
 
       - run: python -Im pip install -e .[dev]

.python-version-default

@@ -0,0 +1 @@
+3.12