be more judicious in string replacements

init script broke because the image was alpine for that
container and this repo's image for the primary container.
the sed replacement clobbered both, rendering the init
inoperable.

.github/workflows/build.yaml

@@ -21,7 +21,7 @@ jobs:
             docker tag "`cat iid.txt`" "$DOCKER_REGISTRY/$GITHUB_REPOSITORY:$TAG"
             docker push "$DOCKER_REGISTRY/$GITHUB_REPOSITORY:$TAG"
           done
-          sed -i -e "s@image: .*@image: $DOCKER_REGISTRY/$GITHUB_REPOSITORY:$STAG@" k/runner.yaml
+          sed -i -e "s@image: $DOCKER_REGISTRY/$GITHUB_REPOSITORY:.*@image: $DOCKER_REGISTRY/$GITHUB_REPOSITORY:$STAG@" k/runner.yaml
           git config user.name "$GITHUB_REPOSITORY (act)"
           git config user.email "gitea-actions@strudelline.net"
           git add k/runner.yaml

k/runner.yaml

@@ -36,7 +36,7 @@ spec:
       - name: docker-certs
         emptyDir: {}
       initContainers:
-        - image: git.strudelline.net/cascade/docker-act_runner:main-2024-03-29-02.31.25
+        - image: alpine:3.19
           imagePullPolicy: IfNotPresent
           name: chowner
           volumeMounts: