keep running tests even if earlier ones failed

Matt Pickering says we should always run all tests. This uses
`continue-on-error: true` to run them as long as the build
succeeded.

.github/workflows/validate.yml

@@ -218,23 +218,29 @@ jobs:
           # `rawSystemStdInOut reports text decoding errors`
           # test does not find ghc without the full path in windows
           GHCPATH: ${{ steps.setup-haskell.outputs.ghc-exe }}
+        continue-on-error: true
         run: sh validate.sh $FLAGS -s lib-tests
 
       - name: Validate lib-suite
+        continue-on-error: true
         run: sh validate.sh $FLAGS -s lib-suite
 
       - name: Validate cli-tests
+        continue-on-error: true
         run: sh validate.sh $FLAGS -s cli-tests
 
       - name: Validate cli-suite
+        continue-on-error: true
         run: sh validate.sh $FLAGS -s cli-suite
 
       - name: Validate solver-benchmarks-tests
         if: matrix.ghc == env.GHC_FOR_SOLVER_BENCHMARKS
+        continue-on-error: true
         run: sh validate.sh $FLAGS -s solver-benchmarks-tests
 
       - name: Validate solver-benchmarks-run
         if: matrix.ghc == env.GHC_FOR_SOLVER_BENCHMARKS
+        continue-on-error: true
         run: sh validate.sh $FLAGS -s solver-benchmarks-run
 
   validate-old-ghcs:
@@ -289,11 +295,13 @@ jobs:
           restore-keys: ${{ runner.os }}-${{ env.GHC_FOR_RELEASE }}-
 
       - name: Validate build
+        id: build
         run: sh validate.sh ${{ env.COMMON_FLAGS }} -s build
 
       - name: "Validate lib-suite-extras --extra-hc ghc-${{ matrix.extra-ghc }}"
         env:
           EXTRA_GHC: ghc-${{ matrix.extra-ghc }}
+        continue-on-error: true
         run: sh validate.sh ${{ env.COMMON_FLAGS }} --lib-only -s lib-suite-extras --extra-hc "${{ env.EXTRA_GHC }}"
 
   build-alpine: