resources: Fix incorrect URL for 'arm64-ubuntu-20.04'

Change-Id: I971d3d55d5cbfb8ca21c4fae6a747f0c6f4a8989
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-resources/+/59570
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
diff --git a/resources.json b/resources.json
index b5d8bfc..65318cf 100644
--- a/resources.json
+++ b/resources.json
@@ -126,7 +126,7 @@
             "architecture" : "ARM",
             "is_zipped" : true,
             "md5sum" : "708cafd0591b2cdd03179b494f7bbf1f",
-            "url" : "{url_base}/images/arm/ubuntu-20-04/arm64-ubuntu-20220425.img.gz",
+            "url" : "{url_base}/images/arm/ubuntu-20-04/arm64-ubuntu-20220509.img.gz",
             "source" : "src/arm-ubuntu",
             "additional_metadata" : {
                 "root_partition": "1"