linters: Fix check-version-number

This should have used `grep -E`, not `grep -e`

.gitlab/linters/check-version-number.sh

@@ -2,5 +2,5 @@
 
 set -e
 
-grep -e -q '\[[0-9]+\.[0-9]+\.[0-9]+\]' configure.ac ||
+grep -E -q '\[[0-9]+\.[0-9]+\.[0-9]+\]' configure.ac ||
   ( echo "error: configure.ac: GHC version number must have three components."; exit 1 )