errbot 6.2.1 with xmpp not compatible with py3.10

[nzlosh]

Describe the bug
Installation of errbot 6.2.1 when installing xmpp using python3.10 will fail with an unsatisfied dependency.

ERROR: Could not find a version that satisfies the requirement slixmpp==1.15.0; extra == "xmpp" (from errbot[irc,xmpp]) (from versions: 1.8.0.linux-x86_64, 1.0.post1, 1.0.post2, 1.0.post3, 1.0.post4, 1.0.post5, 1.1, 1.2, 1.2.1, 1.2.2, 1.2.3, 1.2.4, 1.2.4.post1, 1.3.0, 1.4.0, 1.4.1, 1.4.2, 1.5.0, 1.5.1, 1.5.2, 1.6.0, 1.7.0, 1.7.1, 1.8.0.1, 1.8.1, 1.8.2, 1.8.3, 1.8.4, 1.8.5, 1.8.6, 1.9.0, 1.9.1, 1.10.0, 1.11.0, 1.12.0)
ERROR: No matching distribution found for slixmpp==1.15.0; extra == "xmpp"

To Reproduce

1. Create vitrual env with python3.10

python3 -m venv venv

2. Install errbot 6.2.1 with xmpp

source venv/bin/activate
pip install errbot[xmpp]==6.2.1

Expected behavior
Errbot is installed with xmpp.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• Errbot version:
• OS version: Ubuntu 22.04.5 LTS
• Python version: Python 3.10.12
• Using a virtual environment: yes
• Using Docker: no

Additional context

[sijis]

@nzlosh would you be able to validate if this patch resolve the problem and xmpp works? #1771