Update changelog for release 3.3.0

Add 'release' workflow to create a GH release on tags

This should help the conda-forge bot to pick up new releases faster.

Add CONDA_DEVENV_USE_LOCKS env var to configure the default for --use…

…-locks

Fix platform selectors of included files when rendering lock files

The platform selectors (`[win]`, `[linux]`, etc) for files included via `includes:`
were not being honored when rendering lock files for all platforms.

The bug was that the `CondaPlatform` instance, which configures selectors
explicitly, was not being passed along to the function which handled the `includes` directive.

To make this error less likely to happen again, the `conda_platform` parameter is no longer optional.

Release 3.1.0

Release 3.0.0

Update CHANGELOG date

Update 2.3.0 release date (#137)

Fix RST syntax in README.rst

Correctly handle pip deps with flags (#114)

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>
Co-authored-by: Bruno Oliveira <bruno@esss.com.br>