grpc: avoid a mypy warning

Suddenly, completely out of the blue as far as I'm concerned, mypy
started alerting on this import. Silence the silliness.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

sambacc/grpc/backend.py

@@ -134,7 +134,7 @@ def _samba_version(self) -> str:
 
     def _sambacc_version(self) -> str:
         try:
-            import sambacc._version
+            import sambacc._version  # type: ignore
 
             return sambacc._version.version
         except ImportError: