Set codecov upload token

Docs seem to indicate this should only be required for private
repos, but we have builds failing claiming this needs to be
specified, so just set it manually.

Author: TheBlueMatt

.github/workflows/build.yml

@@ -71,6 +71,7 @@ jobs:
         if: matrix.coverage
         uses: codecov/codecov-action@v1
         with:
+          token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true
 
   fuzz: