Allow the unused_braces lint which is too eager

See rust-lang/rust#70717

Author: shepmaster

.cirrus.yml

@@ -42,7 +42,8 @@ doc_test_task:
   version_information_script:
     - rustc +nightly --version
   docs_script:
-    - cargo +nightly doc
+    # unused-braces is due to https://github.com/rust-lang/rust/issues/70717
+    - RUSTFLAGS='-D warnings -A unused-braces' RUSTDOCFLAGS=$RUSTFLAGS cargo +nightly doc
   backtraces_docs_script:
     - cargo +nightly doc --features=backtraces
   backtraces_impl_backtrace_crate_docs_script: