Add coverage to CI

Author: Frankie Robertson

.github/workflows/CI.yml

@@ -44,7 +44,11 @@ jobs:
       - uses: julia-actions/julia-buildpkg@v1
       - name: Run tests
         run: |
-          cd test && julia --project=. ./runtests.jl
+          cd test && julia --project=. --code-coverage=user ./runtests.jl
+      - uses: julia-actions/julia-processcoverage@v1
+      - uses: coverallsapp/github-action@v2
+        with:
+          file: lcov.info
   docs:
     name: Documentation
     runs-on: ubuntu-latest