regex: tweak DFA settings

This increases the limits a bit for when the regex engine will build and
use a fully compiled DFA. They can faster in some circumstances. For
example, '(?-u)^\w{30,}$' gets a nice speed boost from state
acceleration.

We are also able to remove `regex` proper as a dependency. Wow.

crates/regex/Cargo.toml

@@ -18,6 +18,5 @@ aho-corasick = "1.0.2"
 bstr = "1.5.0"
 grep-matcher = { version = "0.1.6", path = "../matcher" }
 log = "0.4.19"
-regex = "1.8.3"
-regex-automata = { version = "0.3.0" }
+regex-automata = "0.3.0"
 regex-syntax = "0.7.2"