refactor: add migration warnings and scheduled outages

.github/workflows/ci.yml

@@ -1,9 +1,6 @@
 name: CI
 on:
   push:
-    branches:
-      - main
-      - develop*
     paths-ignore:
       - '**.md'
   pull_request:

.github/workflows/integration.yml

@@ -1,9 +1,6 @@
 name: MODFLOW 6 integration testing
 on:
   push:
-    branches:
-      - main
-      - develop*
     paths-ignore:
       - '**.md'
   pull_request:

README.md

@@ -6,12 +6,7 @@
 
 An action to setup the [GNU Fortran](https://gcc.gnu.org/fortran/) compiler.
 
-**Note:** [`awvwgk/setup-fortran`](https://github.com/awvwgk/setup-fortran) is recommended for most use cases as it:
-
-- supports a range of GNU compiler toolchain versions
-- tests runner/version compatibility daily
-
-This action has one advantage, however: nothing new is installed to the runner, precluding transient network errors.
+**Note:** Maintenance of this action will cease in 2024. If the GCC preinstalled on runner images does not meet your needs, [`fortran-lang/setup-fortran`](https://github.com/fortran-lang/setup-fortran) is recommended.
 
 <!-- START doctoc generated TOC please keep comment here to allow auto update -->
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

action.yml

@@ -3,6 +3,18 @@ description: Install & cache GNU Fortran
 runs:
   using: composite
   steps:
+    - name: Migration warning
+      shell: bash
+      run: |
+        echo "WARNING: This action will be archived on 01/01/24."
+        echo "Use fortran-lang/setup-fortran instead (https://github.com/fortran-lang/setup-fortran)."
+
+    - name: Migration brownout
+      uses: wpbonelli/schedule-outage@v1
+      with:
+        probability: 0.1
+        message: "This action will be archived on 01/01/24. Use fortran-lang/setup-fortran instead (https://github.com/fortran-lang/setup-fortran)."
+
     - name: Symlink to gfortran (Linux)
       if: runner.os == 'Linux'
       shell: bash