Pyaml-env

What's Changed
* Update codeql analysis by lukeanderson93 in https://github.com/mkaranasou/pyaml_env/pull/39
* Fix SyntaxWarning: invalid escape sequence. by lukeanderson93 in https://github.com/mkaranasou/pyaml_env/pull/37
* Update python-publish.yml by mkaranasou in https://github.com/mkaranasou/pyaml_env/pull/40
* Revert "Update python-publish.yml" by mkaranasou in https://github.com/mkaranasou/pyaml_env/pull/41

New Contributors
* lukeanderson93 made their first contribution in https://github.com/mkaranasou/pyaml_env/pull/39

**Full Changelog**: https://github.com/mkaranasou/pyaml_env/compare/v1.2.1...v1.2.2

Resolves issue 30

- [x] You can now enforce datatype of environment variable or default value with `tag:yaml.org,2002:datatype` e.g. `tag:yaml.org,2002:float` (workaround because `!!float` is not allowed when there is an `!ENV` tag. (see 26 )
- [x] Bug fix: parse only environment variables that are denoted with `!ENV` tag, not any environment variable (see 25 )

- [X] Minor change in requirements.txt to allow PyYAML 6.* too.

**Changelog:**
- [X] Added an encoding option for opening files - defaults to utf-8
- [X] Handling of `default_value=None`

Adding `loader` kwarg to `parse_config` to address 17 .