tests: Update weekly test docker image tags to v22-1

Change-Id: I6a7ff942234f65b763d2974deb740942bfc2cc17
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65922
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/tests/weekly.sh b/tests/weekly.sh
index c7f834b..9b400b9 100755
--- a/tests/weekly.sh
+++ b/tests/weekly.sh
@@ -37,7 +37,7 @@
 
 # The docker tag to use (varies between develop, and versions on the staging
 # branch)
-tag="latest"
+tag="v22-1"
 
 # We assume the first two arguments are the number of threads followed by the
 # GPU ISA to test. These default to 1 and GCN3_X86 is no argument is given.