Don't include pr/* labels when creating backports (#117)

To avoid creating a PR with `pr/last-call`.

Signed-off-by: Yarden Shoham <[email protected]>

src/github.ts

@@ -362,15 +362,16 @@ export const createBackportPr = async (
   });
   const json = await response.json();
 
-  // filter lgtm/*, backport/*, reviewed/*, and size/* labels
+  // filter lgtm/*, backport/*, reviewed/*, size/*, and pr/* labels
   const labels = originalPr.labels
     .map((label) => label.name)
     .filter((label) => {
       return (
         !label.startsWith("lgtm/") &&
         !label.startsWith("backport/") &&
         !label.startsWith("reviewed/") &&
-        !label.startsWith("size/")
+        !label.startsWith("size/") &&
+        !label.startsWith("pr/")
       );
     });