Credit icons8.com in about window

[digitalteg]

Expected to see credit given to icons8.com in about window

Steps to Reproduce

1. Open Help/About

Expected Behavior

Expected to see credit given to icons8.com for database icons included in keepassxc

Actual Behavior

Did not see credit given to icons8.com for database icons included in keepassxc

Context

#4699

Debug Info:
KeePassXC - Version 2.6.4
Revision: 34a78f0
Distribution: AppImage

Qt 5.15.2
Debugging mode is disabled.

Operating system: Devuan GNU/Linux 3 (beowulf)
CPU architecture: x86_64
Kernel: linux 4.19.0-12-amd64

Enabled extensions:

• Auto-Type
• Browser Integration
• SSH Agent
• KeeShare (signed and unsigned sharing)
• YubiKey
• Secret Service Integration

Cryptographic libraries:

• libgcrypt 1.8.1

Operating System: Linux
Desktop Env: KDE
Windowing System: X11

[droidmonkey]

All icons were derived from https://github.com/icons8/flat-color-icons which requires no credits. Also a good number were subsequently modified by me or created by me from scratch. All our crediting is appropriately within the https://www.github.com/keepassxreboot/keepassxc/tree/develop/COPYING file.