dockerimg: add 'apk add grep'

Claude wants to use lots of grep features that the busybox version lacks.

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/dockerimg/testdata/testcreatedockerfile_empty_repo.dockerfile b/dockerimg/testdata/testcreatedockerfile_empty_repo.dockerfile
index b4ac299..b53e8fa 100644
--- a/dockerimg/testdata/testcreatedockerfile_empty_repo.dockerfile
+++ b/dockerimg/testdata/testcreatedockerfile_empty_repo.dockerfile
@@ -6,14 +6,13 @@
 RUN git config --global user.email "$GIT_USER_EMAIL" && \
     git config --global user.name "$GIT_USER_NAME"
 
-LABEL sketch_context="64e014c23327ab5d33f72661ff9322e1ae3f87ffc6daded9c7f68629cc8f34da"
+LABEL sketch_context="17320ef95f67844208ac1b3e00f1f4dd0951e229517619bdbc8085eba3a7e067"
 COPY . /app
 
 WORKDIR /app
 RUN if [ -f go.mod ]; then go mod download; fi
 
-RUN apk add --no-cache protoc protobuf-dev || true
-RUN go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
-RUN go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
+RUN apk add --no-cache python3 py3-pip || true
+RUN pip3 install --upgrade pip || true
 
 CMD ["/bin/sketch"]