signed types: integer fix

integer was missing from the list of type conversions causing CI to fall over

ChangeLog-None

contrib/msggen/msggen/gen/grpc2py.py

@@ -44,6 +44,7 @@ def __init__(self, dest: TextIO):
             's16': "m.{name}",
             's32': "m.{name}",
             's64': "m.{name}",
+            'integer': "m.{name}",
             'boolean': "m.{name}",
             'short_channel_id': "m.{name}",
             'msat': "amount2msat(m.{name})",