Gerrit.groovy: Use fetch refspec which includes refs/changes/*

To allow testing tf-m-ci-scripts patches submitted to Gerrit.

Related to https://linaro.atlassian.net/browse/TFC-639

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ic501c5983296fb3bd0a3e70dfc3527b078694941
1 file changed