Create patches.cache

ci/build-repo.sh

@@ -168,7 +168,7 @@ build_repo() {
   cp -R $PATCHES tmp/patches
   hackage-repo-tool bootstrap --keys=./keys --repo=./repo
 
-  mkdir -p template patches.cache
+  mkdir -p template tmp/patches.cache
   tool \
     --patches=./tmp/patches \
     --repo-cache=./cache \