chore(deps): update dependency dataclasses to <0.8 (#478)

Author: renovate-bot

packages/gapic-generator/setup.py

@@ -51,7 +51,7 @@
         "protobuf >= 3.12.0",
         "pypandoc >= 1.4",
         "PyYAML >= 5.1.1",
-        "dataclasses < 0.7; python_version < '3.7'"
+        "dataclasses<0.8; python_version < '3.7'"
     ),
     extras_require={':python_version<"3.7"': ("dataclasses >= 0.4",),},
     tests_require=("pyfakefs >= 3.6",),