server() got an unexpected keyword argument 'ssl_context'

**Describe the bug**
TypeError: server() got an unexpected keyword argument 'ssl_context'

**To Reproduce**
Steps to reproduce the behavior:
1. Install gdbgui via pip following this documentation, https://www.gdbgui.com/installation/
2. Generate key and cert files as described in the help (gdbgui -h)
3. Once the key and cert files are ready, run gdbgui with this arguments "--host --cert "

**Expected behavior**
Open gdbgui in a browser window with https in the url.

Opening gdbgui with default browser at https://127.0.0.1:5000
View gdbgui dashboard at https://127.0.0.1:5000/dashboard

**Python Traceback**
Traceback (most recent call last):
File "../myvenv/bin/gdbgui", line 8, in
sys.exit(main())
File "../myvenv/lib/python3.6/site-packages/gdbgui/cli.py", line 258, in main
certificate=args.cert,
File "../myvenv/lib/python3.6/site-packages/gdbgui/server/server.py", line 100, in run_server
**kwargs,
File "../myvenv/lib/python3.6/site-packages/flask_socketio/__init__.py", line 630, in run
run_server()
File "../myvenv/lib/python3.6/site-packages/flask_socketio/__init__.py", line 625, in run_server
log_output=log_output, **kwargs)
TypeError: server() got an unexpected keyword argument 'ssl_context'

**Please complete the following information:**
* OS: rhel8
* gdbgui version (`gdbgui -v`): 0.15.1.0
* gdb version (`gdb -v`): 13.1.0
* browser [e.g. chrome, safari]: Chrome
* python packages (`pip freeze`): Long list. Can post if needed

Start with gdbgui/server/server.py:100 and the call from gdbgui/cli.py:258, then inspect the installed Flask-SocketIO server path that rejects ssl_context. Reproduce the documented certificate and key invocation, and verify that gdbgui starts and opens the dashboard over HTTPS without the TypeError.

Written by the indexing model from the issue text.