add Downgrade test

.github/workflows/Downgrade.yml

@@ -0,0 +1,34 @@
+name: Downgrade
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+    tags: '*'
+
+# Needed to allow julia-actions/cache to delete old caches that it has created
+permissions:
+  actions: write
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        version: ['1.10', '1.11']
+    steps:
+      - uses: actions/checkout@v4
+      - uses: julia-actions/setup-julia@latest
+        with:
+          version: ${{ matrix.version }}
+      - uses: julia-actions/cache@v2
+      - uses: julia-actions/julia-downgrade-compat@v1
+        with:
+          skip: Artifacts, Dates, Downloads, Logging, LinearAlgebra, StaticArrays, Statistics, Test
+      - uses: julia-actions/julia-buildpkg@latest
+      - uses: julia-actions/julia-runtest@latest

NEWS.md

@@ -36,6 +36,7 @@ for our diagnostics, the PostProcessor module is not needed.
 This PR follows directly from the Diagnostics module removal.
 
 ### Maintenance
+- Add Downgrade test to CI. PR [#1072](https://github.com/CliMA/ClimaCoupler.jl/pull/1072)
 - Update to JuliaFormatter v2. PR [#1024](https://github.com/CliMA/ClimaCoupler.jl/pull/1024)
 - Update CI to use Julia v1.11. Introduce Manifest files for
 Julia 1.11, in addition to the existing generic Manifests. PR [#1026](https://github.com/CliMA/ClimaCoupler.jl/pull/1026)