feat(tests): Add Pipenv and pytest config

pgproto/Pipfile

+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+pg8000 = "*"
+pytest-xdist = "*"
+pytest = "*"
+flake8 = "*"
+black = "*"
+tarantool = "*"
+funcy = "*"
+mypy = "*"
+pytest-clarity = "*"
+prettytable = "*"
+pytest_harvest = "*"
+pytest-repeat = "*"
+msgpack = "*"
+pexpect = "*"
+
+[requires]
+python_version = "3.10"
+
+[scripts]
+fmt = """bash -c "
+set -e -x
+pipenv run black ./test
+"
+"""
+lint = """bash -c "
+set -e -x
+pipenv run flake8 ./test
+pipenv run black ./test --check --diff
+pipenv run mypy ./test
+"
+"""

pgproto/pytest.ini

+[pytest]
+testpaths =
+    test
+addopts =
+    -v --showlocals