Added codecov action.

Author: Peter Somkuti

.github/workflows/codecov.yml

@@ -0,0 +1,18 @@
+name: Codecov
+on: [push, pull_request]
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Set up Julia 1.11.7
+        uses: julia-actions/setup-julia@v2
+        with:
+          version: '1'
+      - uses: julia-actions/julia-buildpkg@v1
+      - uses: julia-actions/julia-runtest@v1
+      - uses: julia-actions/julia-processcoverage@v1
+      - uses: codecov/codecov-action@v5
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_ORG_TOKEN }}