ci: chmod go-w ~/.cache before pkg commands (sr.ht cache is group-writable)

ober

4ec0f07c96f3288ebe4d132aa8abedeaf83050b1

diff --git a/.builds/ci.yml b/.builds/ci.yml
index e637bc2..9d4c647 100644
--- a/.builds/ci.yml
+++ b/.builds/ci.yml
@@ -33,6 +33,7 @@ tasks:
 - package: |
     cd jerboa-fuse
     J="$HOME/jerboa/dist/jerboa"
+    chmod -R go-w "$HOME/.cache"
     "$J" pkg verify
     "$J" pkg policy
     "$J" pkg build