ci: rename synker image to correspond to newly renamed bigbang

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/cc @someoneelse

.gitignore

@@ -8,6 +8,7 @@ certs/
 *rke2.yaml
 
 *tfstate*
+*terraform.lock*
 
 # dependencies
 /node_modules
@@ -18,4 +19,4 @@ npm-debug.log*
 # ignore developer specific files
 # (used frequently in deployments)
 patch.yaml
-notes
\ No newline at end of file
+notes