fix: ensure default helm cache is writable

Signed-off-by: Tyler Gillson <tyler.gillson@gmail.com>

Dockerfile

@@ -32,7 +32,7 @@ COPY pkg/ pkg/
 RUN CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} go build -a -o manager cmd/main.go
 
 RUN chmod 777 /etc /etc/ssl && chmod -R 777 /etc/ssl/certs && \
-    mkdir /charts && chmod -R 777 /charts
+    mkdir /.cache /charts && chmod -R 777 /.cache /charts
 
 # Use distroless as minimal base image to package the manager binary
 # Refer to https://github.com/GoogleContainerTools/distroless for more details
@@ -42,6 +42,7 @@ WORKDIR /
 COPY --from=builder /workspace/manager .
 COPY --from=builder /workspace/helm .
 COPY --from=builder --chown=65532:65532 /etc /etc
+COPY --from=builder --chown=65532:65532 /.cache /.cache
 COPY --from=builder --chown=65532:65532 /charts /charts
 
 USER 65532:65532