Revert "Bump codecov/codecov-action from 3 to 5 (#965)" (#967)

This reverts commit 0538d3d.

Author: jishnub

.github/workflows/ci.yml

@@ -62,6 +62,6 @@ jobs:
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v5
+      - uses: codecov/codecov-action@v3
         with:
           files: lcov.info