Avoid version specific sed syntax

The argument to sed prior to this change triggers something in sed version 4.6 or 4.7

.github/workflows/test_ert.yml

@@ -69,8 +69,8 @@ jobs:
     - name: Test for a clean repository
       run: |
         # Run this before the 'Test CLI' entry below, which produces a few files that are accepted for now. Exclude the wheel.
-        git status --porcelain | sed '/ert.*.whl$\|\/block_storage$/d'
-        test -z "$(git status --porcelain | sed '/ert.*.whl$\\|\\/block_storage$/d')"
+        git status --porcelain | grep -v -e 'ert.*.whl' | grep -v 'block_storage'
+        test -z "$(git status --porcelain | grep -v -e 'ert.*.whl' | grep -v 'block_storage')"
 
     - name: Upload coverage to Codecov
       id: codecov1