"View Source" links on website always link to dynamic `master` branch

"View Source" links on the website always lead to master branch in the GitHub repository, which is subject to changes over time.

For example, for collapsible_match on Rust 1.95.0, the source link points to https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/matches/mod.rs#L659, which is not the expected location as the file was updated since the tag was published. Pointing to the tag (https://github.com/rust-lang/rust-clippy/blob/rust-1.95.0/clippy_lints/src/matches/mod.rs#L659) would ensure that the location stays valid over time.