release: move secrets to workflow environment (git-for-windows#584)

Migrate applicable secrets to a new 'release' workflow environment. This
is a security measure to help ensure secrets cannot be accessed by those
without proper permissions.

An example of a passing `build-git-installers` workflow with these
changes can be found
[here](https://github.com/ldennington/git/actions/runs/5182147378) (I
set up my fork with the same migrated secret values as this repo).

Note that the old actions secrets will be left in this repo until the
next successful release, at which point they can be safely removed.

Author: ldennington

.github/workflows/build-git-installers.yml

@@ -9,6 +9,7 @@ jobs:
   # Check prerequisites for the workflow
   prereqs:
     runs-on: ubuntu-latest
+    environment: release
     env:
       AZ_SUB: ${{ secrets.AZURE_SUBSCRIPTION }}
       AZ_CREDS: ${{ secrets.AZURE_CREDENTIALS }}
@@ -49,6 +50,7 @@ jobs:
   # Build Windows installers (x86_64 installer & portable)
   windows_pkg:
     runs-on: windows-2019
+    environment: release
     needs: prereqs
     env:
       GPG_OPTIONS: "--batch --yes --no-tty --list-options no-show-photos --verify-options no-show-photos --pinentry-mode loopback"
@@ -144,6 +146,7 @@ jobs:
           path: artifacts
   windows_artifacts:
     runs-on: windows-2019
+    environment: release
     needs: [prereqs, windows_pkg]
     env:
       HOME: "${{github.workspace}}\\home"
@@ -370,6 +373,7 @@ jobs:
   osx_sign_payload:
     # ESRP service requires signing to run on Windows
     runs-on: windows-latest
+    environment: release
     needs: osx_build
     steps:
     - name: Check out repository
@@ -477,6 +481,7 @@ jobs:
   osx_sign_and_notarize_pkg:
     # ESRP service requires signing to run on Windows
     runs-on: windows-latest
+    environment: release
     needs: osx_pack
     steps:
     - name: Check out repository
@@ -653,6 +658,7 @@ jobs:
           path: artifacts/
   ubuntu_sign-artifacts:
     runs-on: windows-latest # Must be run on Windows due to ESRP executable OS compatibility
+    environment: release
     needs: [ubuntu_build, prereqs]
     if: needs.prereqs.outputs.deb_signable == 'true'
     env:

.github/workflows/release-apt-get.yml

@@ -13,6 +13,7 @@ on:
 jobs:
   release:
     runs-on: ubuntu-latest
+    environment: release
     steps:
       - uses: actions/checkout@v3
 

.github/workflows/release-homebrew.yml

@@ -6,6 +6,7 @@ on:
 jobs:
   release:
     runs-on: ubuntu-latest
+    environment: release
     steps:
     - id: version
       name: Compute version number

.github/workflows/release-winget.yml

@@ -13,6 +13,7 @@ on:
 jobs:
   release:
     runs-on: windows-latest
+    environment: release
     steps:
       - name: Publish manifest with winget-create
         run: |