ci: set umask 022 to prevent group-writable cache dirs (sr.ht default umask creates 0775 dirs)

ober

463dd4c35ad88bb1310bcbe1d4b530f291be9eb1

diff --git a/.builds/ci.yml b/.builds/ci.yml
index bd9d235..b3f0ce9 100644
--- a/.builds/ci.yml
+++ b/.builds/ci.yml
@@ -23,6 +23,7 @@ artifacts:
 - jerboa-qt/jerboa-qt-0.1.0.jpkg
 tasks:
 - build-jerboa: |
+    umask 022
     cd jerboa
     sudo fallocate -l 4G /swapfile && sudo chmod 600 /swapfile && sudo mkswap /swapfile && sudo swapon /swapfile
     export CARGO_BUILD_JOBS=1