Update CI config (#99)

* Update CI config

- use `julia-actions/cache` instead of `actions/cache`
- test macOS on native ARM / aarch64 where applicable
- avoid concurrent PR CI runs
- drop obsolete `file` argument to `codecov/codecov-action`

---------

Co-authored-by: Lilith Orion Hafner <[email protected]>

Author: fingolfin

.github/workflows/CI.yml

@@ -5,6 +5,19 @@ on:
     branches:
       - main
     tags: '*'
+
+concurrency:
+  # group by workflow and ref; the last slightly strange component ensures that for pull
+  # requests, we limit to 1 concurrent job, but for the default repository branch we don't
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.ref_name != github.event.repository.default_branch || github.run_number }}
+  # Cancel intermediate builds, but only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+
+# needed to allow julia-actions/cache to delete old caches that it has created
+permissions:
+  actions: write
+  contents: read
+
 jobs:
   test:
     name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
@@ -23,30 +36,26 @@ jobs:
           - macOS-latest
           - windows-latest
         arch:
-          - x64
+          - ''  # default arch, usually x64 but for macOS also aarch64
           - x86
         exclude:
-          - os: macOS-latest
+          - os: macOS-latest # Apple Silicon
             arch: x86
+          - os: macOS-latest # Apple Silicon
+            version: '1.0'
+            arch: ''
+        include:
+          - os: macOS-latest # Apple Silicon
+            version: '1.0'
+            arch: 'x64'  # run x86_64 build of Julia under Rosetta 2 emulation
     steps:
       - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
-          arch: ${{ matrix.arch }}
-      - uses: actions/cache@v4
-        env:
-          cache-name: cache-artifacts
-        with:
-          path: ~/.julia/artifacts
-          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
-          restore-keys: |
-            ${{ runner.os }}-test-${{ env.cache-name }}-
-            ${{ runner.os }}-test-
-            ${{ runner.os }}-
+          arch: ${{ (matrix.arch == '') && runner.arch || matrix.arch }}
+      - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
       - uses: codecov/codecov-action@v5
-        with:
-          file: lcov.info