bitbake: fetch2: Avoid deprecation warning

>From re on python 3.13 onwards: "Passing count and flags as positional arguments is deprecated.
In future Python versions they will be keyword-only parameters."

Avoid the warning.

(Bitbake rev: 016d872dc3c36792af5c84da1d35a5c86996d795)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/__init__.py

@@ -237,7 +237,7 @@ class URI(object):
         # to RFC compliant URL format. E.g.:
         #   file://foo.diff -> file:foo.diff
         if urlp.scheme in self._netloc_forbidden:
-            uri = re.sub("(?<=:)//(?!/)", "", uri, 1)
+            uri = re.sub(r"(?<=:)//(?!/)", "", uri, count=1)
             reparse = 1
 
         if reparse: