fix: codecov upload

Use the official codecov action, since the bash script is deprecated.
Also set a timeout on upload so we don't block other steps for too long.

Signed-off-by: Noel Georgi <git@frezbo.dev>

.github/workflows/ci.yaml

@@ -1,6 +1,6 @@
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2024-04-20T16:39:33Z by kres add13d7.
+# Generated on 2024-04-30T10:47:51Z by kres ebc009d-dirty.
 
 name: default
 concurrency:
@@ -61,8 +61,11 @@ jobs:
         run: |
           make unit-tests-race
       - name: coverage
-        run: |
-          make coverage
+        uses: codecov/codecov-action@v4
+        with:
+          files: _out/coverage-unit-tests.txt
+          token: ${{ secrets.CODECOV_TOKEN }}
+        timeout-minutes: 3
       - name: kres
         run: |
           make kres