Drop Python 2.6

[hugovk]

Pytest and its dependency py have dropped support for Python 2.6 because it's been EOL for four years meaning it hasn't received security updates, and it's also little used so it's about time to drop it. They also dropped support for Python 3.3 which is also EOL and little used.

Here's the pip installs for prometheus_client from PyPI for the last month (via pypinfo --percent --pip prometheus_client pyversion).

python_version	percent	download_count
2.7	61.2%	44,829
3.6	21.0%	15,367
3.5	13.5%	9,890
3.4	4.0%	2,947
3.7	0.2%	116
2.6	0.1%	87
3.3	0.1%	48
3.2	0.0%	1

I suggest client_python also drops 2.6 (3.3 is already dropped).

[brian-brazil]

RHEL 6 has Python 2.6 and is supported through 2024. The effort to support 2.6 so far has been fairly small.

[ioggstream]

I think we could leave this tkt open as a reminder.

[hugovk]

Feel free to re-open a new ticket, I think I'll close this to clear my list, rather than having this on it for the next 4+ years :)

By the way, here's the numbers for February 2020:

category	percent	downloads
2.7	32.65%	1,863,581
3.6	30.54%	1,742,994
3.7	24.41%	1,392,992
3.5	8.30%	473,979
3.8	3.06%	174,552
null	0.73%	41,653
3.4	0.29%	16,518
3.9	0.01%	501
2.6	0.01%	481
3.3	0.00%	99
Total		5,707,350

Source: pip install -U pypistats && pypistats python_minor prometheus_client --last-month

Cheers!