Merge pull request #494 from MongoEngine/pip_update

CI/CD: Include pip update to nox sessions

Author: insspb

noxfile.py

@@ -14,13 +14,15 @@
 def base_install(session, flask, mongoengine):
     """Create basic environment setup for tests and linting."""
     if flask == "==1.1.4":
+        session.run("python", "-m", "pip", "install", "--upgrade", "pip")
         session.install(
             f"Flask{flask}",
             f"mongoengine{mongoengine}",
             "-e",
             ".[wtf,toolbar,legacy,legacy-dev]",
         )
     else:
+        session.run("python", "-m", "pip", "install", "--upgrade", "pip")
         session.install(
             f"Flask{flask}",
             f"mongoengine{mongoengine}",