[dev-context] CGModules update: vim syntax highlighting version 2021.05.31 published.

Aditya Mahajan submitted an update to the vim syntax highlighting package. Version number: 2021.05.31 License type: BSD License (simplified) Wants to be in ConTeXt distribution: yes Wants to be synced with CTAN: yes Summary description: This module uses Vim editor's syntax files to syntax highlight verbatim code in ConTeXt Announcement text: ---------------------------------------------------------------------- Bugfix release: * Second attempt to fix a bug where `--` was being translated to `–` in LMTX. Previous tests failed because I did not notice that `context --luatex` now invokes MKIV. ----------------------------------------------------------------------