CI: Don't fail fast

We don't want to fail fast.
We used to fail fast, to avoid caches of failing PRs to overpopulate the CI
caches, evicting known good build caches.
However, PRs do not cache anything any more, and can only use the caches from current master.
See 'caching.yml' for our caching set up.

Author: fendor

.github/workflows/test.yml

@@ -61,10 +61,12 @@ jobs:
       - pre_job
     runs-on: ${{ matrix.os }}
     strategy:
-      fail-fast: true
-      # when you edit this list of GHC versions,
-      # **don't forget**
-      # to update the ghc versions in 'caching.yml'.
+      # We don't want to fail fast.
+      # We used to fail fast, to avoid caches of failing PRs to overpopulate the CI
+      # caches, evicting known good build caches.
+      # However, PRs do not cache anything any more, and can only use the caches from current master.
+      # See 'caching.yml' for our caching set up.
+      fail-fast: false
       matrix:
         ghc: ${{ fromJSON(needs.pre_job.outputs.ghcs) }}
         os: