[Windows] Upgrade Inno Setup from 6.0.5 to 6.1.2

See the full changelog.

There is a small note this is important for us:

Change in default behavior: [Setup] section directive MinVersion now defaults to 6.1sp1, so by default Setup will not run on Windows Vista or on versions of Windows 7 and Windows Server 2008 R2 which have not been updated.

This is not a big deal, we are currently using a value set to 6.1.7600 (Windows 7 or Windows Server 2008 R2). We will just remove that value and let Inno Setup handling it using its default one (Windows 7 with Service Pack 1 or Windows Server 2008 R2 with Service Pack 1).
For information the SP1 is from 2011 and any serious company should have done the upgrade since a while: KB976932.

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Actions

• Update unofficial translations, if needed.
• Simply do the upgrade and check that every thing works as expected.
• Document the Windows 7 SP1-only support (and so the Windows 7 not-SP1 unsupport).