cmake: increase required version to 3.22

[nilason]

Increase required CMake version to 3.22 (Nov 2021), replacing current version 3.16 (Nov 2019).

That version would be supported out-of-the-box with, e.g.:

• Debian 12 Bookworm (current stable)
• Fedora 36 (EOL)
• Slackware 15.0 (current stable)
• Ubuntu 22.04 (Jammy Jellyfish, EOL in Apr 2027)

See further platforms: https://repology.org/project/cmake/versions

Otherwise it may be installed through pip.

Version 3.22 comes with a number of useful improvements, among others for Apple ARM platform support, FindGDAL and FindPostgreSQL. See links below for news posts for each upgrade:

https://cmake.org/cmake/help/latest/release/3.17.html
https://cmake.org/cmake/help/latest/release/3.18.html
https://cmake.org/cmake/help/latest/release/3.19.html
https://cmake.org/cmake/help/latest/release/3.20.html
https://cmake.org/cmake/help/latest/release/3.21.html
https://cmake.org/cmake/help/latest/release/3.22.html

[wenzeslaus]

... FindGDAL and FindPostgreSQL.

Can you delete some of the CMake code, then?

[nilason]

... FindGDAL and FindPostgreSQL.

Can you delete some of the CMake code, then?

I have one PR prepared for PostgreSQL (similar to #5263), where we can drop the custom FindPostgreSQL file with 3.20. To mention a concrete example, in fact the reason I started to look at this.

[nilason]

Point of reference: QGIS just bumped to 3.23.