perf: Hash faster for custom dicts

If we have to hash for the custom dict, we might as well be fast about
it.  We do not need a cryptographically secure algorithm since the
content is fixed for the user.

Master:
```
real    0m26.675s
user    0m33.683s
sys     0m4.535s
```

With ahash:
```
real    0m23.993s
user    0m30.800s
sys     0m4.440s
```

Cargo.lock

@@ -1,5 +1,15 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "ahash"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4eb6ec8807cd25b59e6b8100815afc73f54e294f1a425a2e555971969889a8f8"
+dependencies = [
+ "getrandom 0.2.0",
+ "lazy_static",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "0.7.15"
@@ -377,6 +387,17 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee8025cf36f917e6a52cce185b7c7177689b838b7ec138364e50cc2277a56cf4"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "globset"
 version = "0.4.6"
@@ -719,7 +740,7 @@ version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6a6b1679d49b24bbfe0c803429aa1874472f50d9b363131f0e89fc356b544d03"
 dependencies = [
- "getrandom",
+ "getrandom 0.1.15",
  "libc",
  "rand_chacha",
  "rand_core",
@@ -743,7 +764,7 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "90bde5296fc891b0cef12a6d03ddccc162ce7b2aff54160af9338f8d40df6d19"
 dependencies = [
- "getrandom",
+ "getrandom 0.1.15",
 ]
 
 [[package]]
@@ -1051,6 +1072,7 @@ dependencies = [
 name = "typos-cli"
 version = "0.1.4"
 dependencies = [
+ "ahash",
  "anyhow",
  "assert_fs",
  "bstr",

Cargo.toml

@@ -46,6 +46,7 @@ toml = "0.5"
 log = "0.4"
 env_logger = "0.8"
 bstr = "0.2"
+ahash = "0.5.8"
 
 [dev-dependencies]
 assert_fs = "1.0"

src/dict.rs

@@ -144,8 +144,8 @@ fn case_correct(correction: &mut Cow<'_, str>, case: Case) {
 }
 
 pub struct Override<'i, 'w, D> {
-    identifiers: HashMap<&'i str, Status<'i>>,
-    words: HashMap<unicase::UniCase<&'w str>, Status<'w>>,
+    identifiers: HashMap<&'i str, Status<'i>, ahash::RandomState>,
+    words: HashMap<unicase::UniCase<&'w str>, Status<'w>, ahash::RandomState>,
     inner: D,
 }