Don't run goheader on upgrade_strategy.go

goheader in golanci-lint v1.63.2 incorrectly flags these files as having
invalid headers. Root cause not yet known.

Author: swiatekm

.golangci.yaml

@@ -57,6 +57,10 @@ issues:
     - linters:
         - gci
       source: "// \\+kubebuilder"
+    # For some reason goheader complains about these files, even though the headers are correct
+    - linters:
+        - goheader
+      path: upgrade_strategy\.go
 
 linters:
   enable: