lfs: drop an unnecessary r'' prefix

lfs: drop an unnecessary r'' prefix

No longer necessary since the source transformer was removed.

# skip-blame for changing string prefixes

Differential Revision: https://phab.mercurial-scm.org/D7958

--- a/hgext/lfs/blobstore.py	Tue Jan 21 09:51:39 2020 -0500
+++ b/hgext/lfs/blobstore.py	Tue Jan 21 09:55:35 2020 -0500
@@ -491,7 +491,7 @@
                     hint=_(b'run hg verify'),
                 )
             request.data = lfsuploadfile(localstore.open(oid))
-            request.get_method = lambda: r'PUT'
+            request.get_method = lambda: 'PUT'
             request.add_header('Content-Type', 'application/octet-stream')
             request.add_header('Content-Length', len(request.data))