Released Chainer v7.4.0

[ecas...@preferred.jp]

We have released Chainer v7.2.0, please find attached the release note.

This is the release note of v7.4.0. See here for the complete list of solved issues and merged PRs.

As announced previously, Chainer has reduced the release frequency from monthly to once every two months. We have decided to skip v7.3.0 in order to keep the Chainer version up to date with CuPy’s most recent release.

Enhancements

• Allow concat_arrays to be pickable (#8549)

Bug Fixes

• Allow start_methods other than fork on MultiprocessParallelUpdater (#7552)
• Fix backend.copyto for mismatched dtypes to CuPy ndarray (#8043)
• Fix optimizer.use_fp32_update on ChainerX model (#8382, thanks @y1r!)

Documentation

• Fix local_convolution_2d result shape documentation (#8553, thanks @msakai!)
• Update functions.rst (#8557, thanks @husisy!)

Tests

• Remove python 2.7 builds (#8550)
• Use CuPy v7 in CI (#8554)