fix(migrations): bump atlas canary to v1.2.1-c68e9af-canary

No stable atlas release yet ships the Go stdlib fix for CVE-2026-42501;
v1.2.0 (2026-04-10) predates it. Move to the latest canary instead of
the older 103d358 build.

Assisted-by: Claude Code
Signed-off-by: Miguel Martinez Trivino <miguel@chainloop.dev>

Author: migmartri

app/controlplane/Dockerfile.migrations

@@ -1,9 +1,9 @@
 # Container image built by go-releaser that's used to run migrations against the database during deployment
 # See https://atlasgo.io/guides/deploying/image
-# from: arigaio/atlas:v1.2.1-103d358-canary
-# docker run arigaio/atlas@sha256:51919e1a97c97a870cde1cc2fa3976b39fb11796aeb08724686b71a453ce87be version
-# atlas version v1.2.1-103d358-canary
-FROM arigaio/atlas@sha256:51919e1a97c97a870cde1cc2fa3976b39fb11796aeb08724686b71a453ce87be as base
+# from: arigaio/atlas:v1.2.1-c68e9af-canary
+# docker run arigaio/atlas@sha256:43917654d497cd1da547b93f40f5d4fa80bcaee6603c0272fd99ccdcb0d03c92 version
+# atlas version v1.2.1-c68e9af-canary
+FROM arigaio/atlas@sha256:43917654d497cd1da547b93f40f5d4fa80bcaee6603c0272fd99ccdcb0d03c92 as base
 
 FROM scratch
 # Update permissions to make it readable by the user