Update deskutils/charmtimetracker to 1.12.0, latest upstream release.

Changes https://github.com/KDAB/Charm/releases/tag/1.12.0

• qtkeychain is now a mandatory dependency
• the KDAB-internal billing code is no longer optional, but can be user-configured away (I hope by default)
• duplicate idle detection dialog removed
• lots of other small fixes