Minimum Qt version?

[c4rlo]

What is the project's minimum required Qt version at this point? It would be nice to state this somewhere for reference.

As I said in my original PR description for #7783, I've been assuming 5.9.5 as the minimum version, as that was stated in INSTALL.md at the time; but as of #10088, it no longer mentions a minimum version requirement. Instead, we now have:

keepassxc/vcpkg.json

Lines 37 to 40 in c81e4e1

	{
	"name": "qt5",
	"version>=": "5.15.11"
	},

But also:

keepassxc/CMakeLists.txt

Lines 515 to 517 in c81e4e1

	if(Qt5Core_VERSION VERSION_LESS "5.2.0")
	message(FATAL_ERROR "Qt version 5.2.0 or higher is required")
	endif()

(Currently, my #7783 includes a commit to change the above to require 5.9.5.)

I ask because there are a bunch of QT_VERSION_CHECKs in the code (including some new ones in #7783), some of which could potentially be deleted now, depending on the minimum Qt version we want to impose. I'd be happy to submit a PR for that cleanup, if I knew which Qt version to target. (Of course, we eventually want to migrate to Qt 6, in #10267, but that might be a while yet I imagine.)

[droidmonkey]

We are bumping it to 5.12 then 6.6 (I think that's the current lts)