v0.1.2

Use setuptools_scm (#48)

* Use setuptools_scm

Follows up https://github.com/ufoym/imbalanced-dataset-sampler/pull/47

- on [pypi](https://pypi.org/project/torchsampler/0.1.1/) it's 0.1.1
- on github it's [0.1.0](https://github.com/ufoym/imbalanced-dataset-sampler/releases/tag/v0.1.0)
    - but the attached [wheel](https://github.com/ufoym/imbalanced-dataset-sampler/releases/download/v0.1.0/torchsampler-0.1.1-py3-none-any.whl)
      and [sdist](https://github.com/ufoym/imbalanced-dataset-sampler/releases/download/v0.1.0/torchsampler-0.1.1.tar.gz) are 0.1.1

[`setuptools-scm`](https://pypi.org/project/setuptools-scm/) makes git the single-source of truth
for the version of the package, and works well with the build script in #47 (which is triggered
by tagging a new version in git).

`setuptools-scm` also replaces most of MANIFEST.in, so this removes the
redundant lines from that too.

* Deprecate torchsampler.__about__

It's better to keep all metadata in setup.py and use importlib.metadata.
Otherwise, you need to 'import __about__' during the build process
means importlib-metadata needs to be installed during the build
if building on python 3.6 or python 3.7, and potentially running an
unbounded amount of other code during the build.

It's easier to just sidestep the issue.

* Squash a build warning

> .../site-packages/setuptools/dist.py:726: UserWarning: Usage of dash-separated 'description-file' will not be supported in future versions. Please use the underscore name 'description_file' instead

description_file has been superseded recently in
4c4a6e3d9a819b3cd7c3b9e580d28254351ec833 anyway.

v0.1.0

Fix homepage