CI: build against ghc-8.10

.gitlab-ci.yml

@@ -72,6 +72,16 @@ build-8.8:
     - branches
     - merge_requests
 
+# Build against the 8.10 branch
+build-8.10:
+  extends: .build
+  variables:
+    GHC_TARBALL: "https://gitlab.haskell.org/api/v4/projects/1/jobs/artifacts/ghc-8.10/raw/ghc-x86_64-fedora27-linux.tar.xz?job=validate-x86_64-linux-fedora27"
+    EXTRA_HC_OPTS: "-dcore-lint"
+  only:
+    - branches
+    - merge_requests
+
 .build:
   stage: test