enables configuration of tbc-check image

templates/validation.yml

@@ -8,6 +8,10 @@ spec:
       description: tags to filter applicable runners for tbc-checklinks build job
       type: array
       default: []
+    tbc-check-image:
+      description: image to use for tbc-check job
+      type: string
+      default: registry.gitlab.com/to-be-continuous/tools/tbc-check:latest
 
 ---
 
@@ -86,7 +90,7 @@ check-links:
 
 tbc-check:
   image:
-    name: registry.gitlab.com/to-be-continuous/tools/tbc-check:latest
+    name: $[[ inputs.tbc-check-image ]]
     entrypoint: [""]
   stage: build
   script: