Drop Python 3.7 and update GitHub Actions to build with Python 3.12.0-rc.3

flake8's latest version for Python 3.7 failed to parse f-strings correctly when running on Python 3.12, giving:

--ignore=E501,E126,W503 email_validator tests
email_validator/syntax.py:30:24: E231 missing whitespace after ':'
email_validator/syntax.py:32:24: E231 missing whitespace after ':'
```

By dropping 3.7 we can update flake8 to work on all other versions.

See https://github.com/actions/python-versions/releases for the Python versions supported in GitHub Actions.

Author: JoshData

.github/workflows/test_and_build.yaml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12.0-alpha.5"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12.0-rc.3"]
 
     steps:
       - uses: actions/checkout@v3

test_requirements.txt

@@ -1,30 +1,26 @@
 # This file was generated by running:
-#   sudo docker run --rm -it --network=host python:3.7-slim /bin/bash
+#   sudo docker run --rm -it --network=host python:3.8-slim /bin/bash
 #   pip install dnspython idna # from setup.cfg
 #   pip install pytest pytest-cov coverage flake8 mypy
 #   pip freeze
 # (Some packages' latest versions may not be compatible with
 # the earliest Python version we support, and some exception
 # messages may depend on package versions, so we pin versions
 # for reproducible testing.)
-attrs==22.2.0
-coverage==7.2.1
-dnspython==2.3.0
-exceptiongroup==1.1.0
-flake8==5.0.4
+coverage==7.3.1
+dnspython==2.4.2
+exceptiongroup==1.1.3
+flake8==6.1.0
 idna==3.4
-importlib-metadata==4.2.0
 iniconfig==2.0.0
 mccabe==0.7.0
-mypy==1.0.1
+mypy==1.5.1
 mypy-extensions==1.0.0
-packaging==23.0
-pluggy==1.0.0
-pycodestyle==2.9.1
-pyflakes==2.5.0
-pytest==7.2.1
-pytest-cov==4.0.0
+packaging==23.1
+pluggy==1.3.0
+pycodestyle==2.11.0
+pyflakes==3.1.0
+pytest==7.4.2
+pytest-cov==4.1.0
 tomli==2.0.1
-typed-ast==1.5.4
-typing_extensions==4.5.0
-zipp==3.15.0
+typing_extensions==4.8.0