Add regex and lazy_static crates

Cargo.lock

@@ -1016,7 +1016,9 @@ dependencies = [
  "epub-builder",
  "html5ever 0.25.1",
  "kuchiki",
+ "lazy_static 1.4.0",
  "md5",
+ "regex",
  "structopt",
  "surf",
  "url",
@@ -1393,9 +1395,9 @@ checksum = "2439c63f3f6139d1b57529d16bc3b8bb855230c8efcc5d3a896c8bea7c3b1e84"
 
 [[package]]
 name = "regex"
-version = "1.3.7"
+version = "1.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a6020f034922e3194c711b82a627453881bc4682166cabb07134a10c26ba7692"
+checksum = "9c3780fcf44b193bc4d09f36d2a3c87b251da4a046c87795a0d35f4f927ad8e6"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -1405,9 +1407,9 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.6.17"
+version = "0.6.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fe5bd57d1d7414c6b5ed48563a2c855d995ff777729dcd91c369ec7fea395ae"
+checksum = "26412eb97c6b088a6997e05f69403a802a92d520de2f8e63c2b65f9e0f47c4e8"
 
 [[package]]
 name = "remove_dir_all"

Cargo.toml

@@ -12,7 +12,9 @@ async-std = "1.5.0"
 epub-builder = "0.4.5"
 html5ever = "0.25.1"
 kuchiki = "0.8.1"
+lazy_static = "1.3.9"
 md5 = "0.7.0"
+regex = "1.3.9"
 surf = "1.0.3"
 structopt = { version = "0.3" }
 url = "2.1.1"