Auto merge of #13161 - ChayimFriedman2:pi-is-zero, r=jonas-schievink
Auto merge of #13161 - ChayimFriedman2:pi-is-zero, r=jonas-schievink

fix: Lower float literals with underscores

Fixes #13155 (the problem was the `PI` is defined with `_f64` suffix). `PI` is still truncated, though, because `f64` cannot represent the value with full precision.

rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer,rust-analyzer/rust-analyzer