message: bump nightly version
diff: @@ -15,7 +15,7 @@ env:
  RUST_BACKTRACE: 1
  # Pin the nightly toolchain to prevent breakage.
  # This should be occasionally updated.
  - RUST_NIGHTLY_TOOLCHAIN: nightly-2021-03-08
  + RUST_NIGHTLY_TOOLCHAIN: nightly-2021-06-21
  CDN: https://dnglbrstg7yg.cloudfront.net
  jobs:
  