ci: serialize kubernetes integration tests

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

Author: crazy-max

.github/workflows/build.yml

@@ -109,7 +109,7 @@ jobs:
           fi
           testFlags="--run=//worker=$(echo "${{ matrix.worker }}" | sed 's/\+/\\+/g')$"
           case "${{ matrix.worker }}" in
-            docker | docker+containerd | docker@* | docker+containerd@* | remote+multinode)
+            docker | docker+containerd | docker@* | docker+containerd@* | remote+multinode | kubernetes)
               echo "TESTFLAGS=${{ env.TESTFLAGS_DOCKER }} $testFlags" >> $GITHUB_ENV
               ;;
             *)