submodules: update clippy from cd3df6b to 2bcb615

Changes:
````
Refactor some minor things
Use more if-chains
Refactor 'lint_or_fun_call'
Refactor 'check_unwrap_or_default'
Refactor 'check_impl_item'
Add missing field to LitKind::Str
Run update_lints for Unicode lint
Re-add false positive check
Add raw string regression test for useless_format lint
Re-factor useless_format lint
Update Unicode lint tests
Add two more tests, allow 2 other lints.
Fix `temporary_cstring_as_ptr` false negative
Add more testcases for redundant_pattern_matching
Fix suggestions for redundant_pattern_matching
Add note on how to find the latest beta commit
Remove feature gate for async_await
Update if_chain doc link
Requested test cleanup
Requested changes
Ignore lines starting with '#'
run-rustfix for unseparated-prefix-literals
Add autofixable suggestion for unseparated integer literal suffices
Further text improvements
Add image
docs: Explain how to update the changelog
````