⬆️ Bump chainer and cupy to 6.2.0, and update other ML/DL deps

Manually updating various machine learning/deep learning dependencies in Pipfile. Detailed references to each updated dependencies' release notes and diff commits as follows:

- [chainer](https://github.com/chainer/chainer) from 6.0.0 to 6.2.0:
  - [Release notes](https://github.com/chainer/chainer/releases/tag/v6.2.0)
  - [Commits](chainer/chainer@v6.0.0...v6.2.0)
- [comet-ml](https://comet.ml/) from 1.0.55 to 2.0.5
- [cupy-cuda100](https://github.com/cupy/cupy) from 6.0.0 to 6.2.0:
  - [Release notes](https://github.com/cupy/cupy/releases/tag/v6.2.0)
  - [Commits](cupy/cupy@v6.0.0...v6.2.0)
- [optuna](https://github.com/pfnet/optuna) from 0.11.0 to 0.13.0
  - [Release notes](https://github.com/pfnet/optuna/releases/tag/v0.13.0)
  - [Commits](optuna/optuna@v0.11.0...v0.13.0)

Author: weiji14

Pipfile

@@ -5,9 +5,9 @@ name = "pypi"
 
 [packages]
 black = "==19.3b0"
-chainer = "==6.0.0"
-comet-ml = "==1.0.55"
-cupy-cuda100 = "==6.0.0"
+chainer = "==6.2.0"
+comet-ml = "==2.0.5"
+cupy-cuda100 = "==6.2.0"
 dask = {extras = ["array"],version = "==1.2.2"}
 descartes = "==1.1.0"
 geopandas = "==0.5.0"
@@ -19,7 +19,7 @@ matplotlib = "==3.1.0"
 netcdf4 = "==1.4.1"
 numpy = "==1.16.4"
 onnx_chainer = "==1.4.1"
-optuna = "==0.11.0"
+optuna = "==0.13.0"
 pandas = "==0.24.2"
 pygmt = {editable = true, ref = "0.0.1a0-40-g29220bd", git = "https://github.com/weiji14/pygmt.git"}
 quilt = "==2.9.15"