tests: disable gpgsign in the git configuration

If the person running the tests has a global configuration to sign git
commits, this breaks the testsuite which looks for a key capable of
committing dummy data under a dummy author

Signed-off-by: Eli Schwartz <eschwartz@archlinux.org>

test/setup.sh

@@ -141,6 +141,7 @@ export GIT_COMMITTER_EMAIL GIT_COMMITTER_NAME
 	mkdir aur.git
 	cd aur.git
 	git init -q
+	git config --local commit.gpgsign false
 
 	git checkout -q --orphan refs/namespaces/foobar/refs/heads/master