Version 1.60.0 release

Merge pull request #19 from getditto/dhm/stable-toolchain

1.57.0 release

Bump to 2021-10-19

Bump to 2021-10-05

Update to nightly-2021-08-01

Co-Authored-By: Daniel Henry-Mantilla <daniel.henry.mantilla@gmail.com>

Update to nightly-2021-09-08

Co-Authored-By: Daniel Henry-Mantilla <daniel.henry.mantilla@gmail.com>

Create nightly 2021-02-25

This contains std::ptr::addr_of, but lacks the ICE bugs that were
introduced in March.

ios-arm64-nightly-2021-03-24

Update from Rust 1.46 to nightly-2021-01-25