Update pbr from 5.1.1 to 5.1.2 (#4526)

requirements/dev.txt

@@ -75,9 +75,9 @@ scandir==1.9.0; python_version < '3.5' \
 
 # Required by mock
 funcsigs==1.0.2 --hash=sha256:330cc27ccbf7f1e992e69fef78261dc7c6569012cf397db8d3de0234e6c937ca
-pbr==5.1.1 \
-    --hash=sha256:f6d5b23f226a2ba58e14e49aa3b1bfaf814d0199144b95d78458212444de1387 \
-    --hash=sha256:f59d71442f9ece3dffc17bc36575768e1ee9967756e6b6535f0ee1f0054c3d68
+pbr==5.1.2 \
+    --hash=sha256:a7953f66e1f82e4b061f43096a4bcc058f7d3d41de9b94ac871770e8bdd831a2 \
+    --hash=sha256:d717573351cfe09f49df61906cd272abaa759b3e91744396b804965ff7bff38b
 
 # Required by responses
 cookies==2.2.1; python_version < '3.4' --hash=sha256:15bee753002dff684987b8df8c235288eb8d45f8191ae056254812dfd42c81d3