install_pmbootstrap: make pmaports/.git world writeable by all (MR 10)

Works around an issue in the CI after the migration where some dirs are
created that are owned by root and not writeable by any other groups/
users.

One way the CI failed from this is .git/refs/remotes was only
writeable by root, since root ran `git remote add` on the freshly cloned
repo causing the remotes dir to be created. Later in CI, when other
users tried to add remotes, these failed silently (thanks git) and the
CI job crashed when it tried to run `git fetch` on the remote that was
never added. At this point in the script, refs/remotes exists so this
chmod "fixes" the issue.

I don't have any idea why this is a problem *now* and not when we were
on gitlab.com.

install_pmbootstrap.sh

@@ -35,6 +35,10 @@ add_remote_origin_original() {
 		cat /tmp/git_remote_add
 		exit 1
 	fi
+
+	# Make sure everyone can write to the repo later, since CI runs as several
+	# different users (root, TESTUSER/pmos, build)
+	chmod -R go+w "$pmaports/.git"
 }
 
 # Set up depends