Pyhocon

* fix(tox): remove old EOLed python 3.x versions, added new python versions (pierresouchay) [330]
* substitution fix (carolguo-dd, darthbear) [308] [329]
* period parser fix (pierresouchay, darthbear) [326] [327] [328]
* fix(config_parser): handle substitutions with resolved values of type ConfigValues (M0dEx) [322]
* Added support for triple quoted keys (jakub-szewczyk-exa) [318]
* Fixed typos and spellings (jsoref) [315]

* Update pyparsing requirement from ~=2.0 to >=2,<4 (ecederstrand) [296]
* Fixes for dict substitution (USSX-Hares) [292]
* Fix: Tests on Windows (USSX-Hares) [291]
* Fix broken overrides (afanasev) [287]

* Resolve namespace package (yifeitao) [264]
* Update pyparsing requires lock to be more strict [275]

* Adding the resolve method to resolve substitution keys in 1 config tree with another config tree (borissmidt) [266]
* Support serializing timedelta and relativedelta to string (hocon, json etc.) (gabis-precog) [263]
* Upgrade to GitHub-native Dependabot (dependabot-preview) [260]
* Process substitution overrides in order (JettJones) [257]
* Fix duration parsing in lists (olii) [255]
* Add support for Python 3.9 and fix deprecation warning (olii) [254]

* Rewrite the logic to resolve package-relative paths so we can remove the "asset" library (klamann) [247]

* fix include error with chinese strings (xinghaixu) [240]
* Glob-pattern Includes (USSX-Hares) [236]
* Fix parsing of durations/periods (olii) [237]
* Fix config_parser.py docstrings (LysanderGG) [235]