fix(deps): allow protobuf 3.19.5 (#508)

* fix(deps): allow protobuf 3.19.5

* explicitly exclude protobuf 4.21.0

Author: parthea

setup.py

@@ -34,7 +34,7 @@
     "google-cloud-org-policy>=0.1.2, <2.0.0",
     "google-cloud-os-config >= 1.0.0, <2.0.0dev",
     "proto-plus >= 1.22.0, <2.0.0dev",
-    "protobuf >= 3.20.2, <5.0.0dev",
+    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
 ]
 
 extras = {"libcst": "libcst >= 0.2.5"}

testing/constraints-3.7.txt

@@ -12,4 +12,4 @@ google-cloud-org-policy==0.1.2
 google-cloud-os-config==1.0.0
 proto-plus==1.22.0
 libcst==0.2.5
-protobuf==3.20.2
+protobuf==3.19.5