Change URL to development version of ''surgesynthteam_tuningui'' submodule (@ b7e56c5)

[FulopNandor]

When some ''.scl'' and/or ''.kbm'' files are opened in Dexed, or drag-n-dropped simply, Dexed crashes in the cases of:

• the Standalone version of the last official binary release (version 0.9.6) in MS Windows 10 OS, 64-bit
• the DEVBUILD DEBUG Standalone versions built from the current content of the official Dexed repository https://github.com/asb2m10/dexed (@ b6cf2e9):
  -- in MS Windows 10 OS, 64-bit,
  -- in some 32-bit Linux distros (Ubuntu Bionic 18.04 and Raspbian OS bookworm).

In order to fix these errors, it seemed necessary to make minor adjustments to the files in the current version of ''surgesynthteam_tuningui'' (@ 54f9a74) that is included in the Dexed repository. Given that Dexed refers to ''surgesynthteam_tuningui'' as a submodule, an intermediary repository at https://github.com/FulopNandor/surgesynthteam_tuningui was forked to incorporate the necessary modifications while maintaining the original submodule structure of the Dexed repository.

While this change to the intermediary repository is essential for managing the exceptions, it alone cannot prevent all exceptions triggered by certain ''.scl'' and ''.kbm'' files, or their combinations. To further address these errors, additional corrections were required in some of source files of Dexed: these corrections are incorporated in subsequent commits (as of this writing, the latest such a commit is @0684d65).