LCG 100, LbEnv 2069 and other small updates
New features:
- Update default LCG to 100
- Use v35-patches branch for Gaudi (until LHCb is more compatible with Gaudi/master)
- Use latest stable LbEnv 2069 (supports new platforms)
Fixes:
- Fix lookup of ninja for LHCb and above
Improvements:
- VSCode: Improve settings for restructuredtext
- Remove python namespace package patch (slows down runtime)
- Use https protocol for fetching recent upstream commit
Internal changes:
- Remove py3 platform from CI