The key generation example in this repo is not working any more

It raises this exception:
```
writing RSA key
Traceback (most recent call last):
File "Adafruit_CircuitPython_JWT/examples/jwt_simpletest_secrets.py", line 37, in
pk = rsa.PrivateKey.load_pkcs1(private_key)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".cpy_venv/lib/python3.12/site-packages/rsa/key.py", line 125, in load_pkcs1
return method(keyfile)
^^^^^^^^^^^^^^^
File ".cpy_venv/lib/python3.12/site-packages/rsa/key.py", line 612, in _load_pkcs1_pem
der = rsa.pem.load_pem(keyfile, b"RSA PRIVATE KEY")
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".cpy_venv/lib/python3.12/site-packages/rsa/pem.py", line 103, in load_pem
pem_lines = [line for line in _pem_lines(contents, pem_start, pem_end)]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".cpy_venv/lib/python3.12/site-packages/rsa/pem.py", line 77, in _pem_lines
raise ValueError('No PEM start marker "%r" found' % pem_start)
ValueError: No PEM start marker "b'-----BEGIN RSA PRIVATE KEY-----'" found
```

The private key that was generated begins with `-----BEGIN PRIVATE KEY-----`, note the lack of "RSA". I'm guessing that my version of openssl is newer than what this example or the library it uses were written for.

Start with examples/jwt_simpletest_secrets.py at line 37 and inspect how the generated private key is loaded. Reproduce the failure and compare the generated PEM header with the format expected by rsa.PrivateKey.load_pkcs1; done means the example can load the generated key without the PEM marker exception.

Written by the indexing model from the issue text.