Update CI.yml

upgrade codecov action to v4

Author: pnavaro

.github/workflows/CI.yml

@@ -61,7 +61,7 @@ jobs:
         shell: julia --project=. --color=yes {0}
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v2
+      - uses: codecov/codecov-action@v4
         with:
           files: lcov.info
       - uses: coverallsapp/github-action@master