GitHub CI: Update GHC versions for release and testing

Release builds are built with GHC 9.6.5 (up from 9.4.8) which is now
considered a stable and reliable build by the GHC team (although a
version 9.6.6 is coming).  Add testing, not only for 9.8.2, but also
for the new 9.10.1 and continue testing 9.4.8 (which GHCUP labels as
recommended).  And add some comments and delimiters to the CI yaml.

.github/workflows/ci.yml

@@ -4,6 +4,10 @@ name: CI
 on: [ push, pull_request ]
 
 jobs:
+
+  # ------------------------------
+  # Basic linting requirements for new commits
+
   build-check-src:
     name: "Check: code cleanliness"
     runs-on: ubuntu-20.04
@@ -26,6 +30,9 @@ jobs:
           ../.github/workflows/check_confdir.py
           ../.github/workflows/check_symlinks.py
 
+  # ------------------------------
+  # Builds for release, using a reliable and stable version of GHC
+
   build-and-test-ubuntu:
     strategy:
       matrix:
@@ -35,8 +42,8 @@ jobs:
     uses: ./.github/workflows/build-and-test-ubuntu.yml
     with:
       os: ${{ matrix.os }}
-      ghc_version: 9.4.8
-      hls_version: 2.7.0.0
+      ghc_version: 9.6.5
+      hls_version: 2.8.0.0
     secrets: inherit
 
   build-and-test-macos:
@@ -48,28 +55,53 @@ jobs:
     uses: ./.github/workflows/build-and-test-macos.yml
     with:
       os: ${{ matrix.os }}
-      ghc_version: 9.4.8
-      hls_version: 2.7.0.0
+      ghc_version: 9.6.5
+      hls_version: 2.8.0.0
     secrets: inherit
 
-  build-and-test-ghc-latest-ubuntu:
-    name: "Build/Test: GHC latest Ubuntu"
+  # ------------------------------
+  # Tests using other recent versions of GHC, particularly newer ones,
+  # in anticipation of upgrading the release builds to that version
+
+  build-and-test-ghc-ubuntu:
+    strategy:
+      matrix:
+        ghc:
+          - version: 9.4.8
+            hls: 2.7.0.0
+          - version: 9.8.2
+            hls: 2.7.0.0
+          - version: 9.10.1
+            hls:
+    name: "Build/Test: GHC Ubuntu"
     uses: ./.github/workflows/build-and-test-ubuntu.yml
     with:
       os: ubuntu-22.04
-      ghc_version: 9.8.2
-      hls_version: 2.7.0.0
+      ghc_version: ${{ matrix.ghc.version }}
+      hls_version: ${{ matrix.ghc.hls }}
     secrets: inherit
 
-  build-and-test-ghc-latest-macos:
-    name: "Build/Test: GHC latest macOS"
+  build-and-test-ghc-macos:
+    strategy:
+      matrix:
+        ghc:
+          - version: 9.4.8
+            hls: 2.7.0.0
+          - version: 9.8.2
+            hls: 2.7.0.0
+          - version: 9.10.1
+            hls:
+    name: "Build/Test: GHC macOS"
     uses: ./.github/workflows/build-and-test-macos.yml
     with:
       os: macos-14
-      ghc_version: 9.8.2
-      hls_version: 2.7.0.0
+      ghc_version: ${{ matrix.ghc.version }}
+      hls_version: ${{ matrix.ghc.hls }}
     secrets: inherit
 
+  # ------------------------------
+  # Test the building of documentation
+
   build-doc-ubuntu:
     strategy:
       matrix:
@@ -149,6 +181,9 @@ jobs:
           name: ${{matrix.os}}-doc-not-tar
           path: inst/doc
 
+  # ------------------------------
+  # Build platform-generic documents for releases
+
   build-releasenotes-ubuntu:
     # Release Notes only need to be built once, so we build on recent
     # Ubuntu, not Mac OS.  Later, the release script will copy the