ci: add git config user.email (#2799)

See if this prevents intermittent git push problems in GitHub Actions.
Most recent failure on 2022-01-09:
https://github.com/SumoLogic/sumologic-kubernetes-collection/actions/runs/3871703022/jobs/6599746510#step:3:276

ci/_build_functions.sh

@@ -17,6 +17,7 @@ function helm() {
 }
 
 function set_up_github() {
+  git config --global user.email "[email protected]"
   git config --global user.name "Continuous Integration [bot]"
 }