Update docker.io/curlimages/curl Docker tag to v8.21.0

molecule-shared/vars.yml

@@ -7,7 +7,7 @@
 # no host port - exactly as in a real deployment. Publishing one for the test would collide
 # between scenarios running in parallel.
 # renovate: datasource=docker depName=docker.io/curlimages/curl
-molecule_shared_image_curl: "docker.io/curlimages/curl:8.11.1"
+molecule_shared_image_curl: "docker.io/curlimages/curl:8.21.0"
 
 # Used for small stub services (a fake homeserver, and so on).
 # renovate: datasource=docker depName=docker.io/library/python