chore(deps): update docker.io/library/golang docker tag to v1.21.5

This MR contains the following updates:

Package	Update	Change
docker.io/library/golang	patch	1.21.4-bookworm -> 1.21.5-bookworm

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images/mirror/Earthfile

@@ -17,7 +17,7 @@ distroless-static:
     DO +MIRROR --image=gcr.io/distroless/static:nonroot@sha256:91ca4720011393f4d4cab3a01fa5814ee2714b7d40e6c74f2505f74168398ca9
 
 golang:
-    DO +MIRROR --image=docker.io/library/golang:1.21.4-bookworm
+    DO +MIRROR --image=docker.io/library/golang:1.21.5-bookworm
 
 alpine:
     DO +MIRROR --image=docker.io/library/alpine:3.18.5