[NFC] Fix exception in version-check.py script

.github/workflows/version-check.py

diff --git a/.github/workflows/version-check.py b/.github/workflows/version-check.py
index f2cef9f..d052bd3 100755
--- a/.github/workflows/version-check.py
+++ b/.github/workflows/version-check.py
@@ -12,7 +12,7 @@
             # We have an rc tag.
             return m.group(1,2,3)
         # We have a final release tag.
-        return (m.group(1), m.group(2), int(m.group(3)) + 1)
+        return (m.group(1), m.group(2), str(int(m.group(3)) + 1))
 
     m = re.match('llvmorg-([0-9]+)-init', tag)
     if m: