Add 'perf' feature flag on regex crate

Our grok crate is unusual. We use regex in certain places like date parsing and
onig when dealing with the grok patterns themselves. Work on #11206 strongly
suggests that if sinks are allowed to run less subject to slow receiver issue
then `apply_date_filter` is a CPU hotspot. As suggested by @tobz we enable the
'perf' flags to the regex crate, which features heavily in the implementation of
that function.

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>

lib/datadog/grok/Cargo.toml

@@ -17,7 +17,7 @@ once_cell = { version = "1.9", default-features = false, features = ["std", "par
 onig = { version = "6.3", default-features = false }
 ordered-float = { version = "2", default-features = false }
 peeking_take_while = { version = "1.0.0", default-features = false }
-regex = { version = "1", default-features = false }
+regex = { version = "1.5", default-features = false, features = ["perf"] }
 serde = { version = "1.0.136", default-features = false  }
 serde_json = { version = "1.0.78", default-features = false }
 strum_macros = { version = "0.23", default-features = false }