Bump codecov/codecov-action from 2 to 3 (#68)

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -39,7 +39,7 @@ jobs:
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v2
+      - uses: codecov/codecov-action@v3
         with:
           files: lcov.info
   docs: