Reduce size of the binary by disabling some rarely used unicode features.

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22 +22 @@
-regex = "1.5"
+regex = { version = "1.5", default-features = false, features = ["std", "unicode-case", "unicode-gencat", "unicode-perl"] }
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3,15 +3,6 @@
 version = 3
 
 [[package]]
-name = "aho-corasick"
-version = "0.7.18"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e37cfd5e7657ada45f742d6e99ca5788580b5c529dc78faf11ece6dc702656f"
-dependencies = [
- "memchr",
-]
-
-[[package]]
 name = "autocfg"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -92,12 +83,6 @@
 ]
 
 [[package]]
-name = "memchr"
-version = "2.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
-
-[[package]]
 name = "memoffset"
 version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -182,8 +167,6 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d83f127d94bdbcda4c8cc2e50f6f84f4b611f69c902699ca385a39c3a75f9ff1"
 dependencies = [
- "aho-corasick",
- "memchr",
  "regex-syntax",
 ]
 
