feat: implement idempotency tokens

closes #108 and closes #106

Cargo.lock

@@ -27,6 +27,17 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 
+[[package]]
+name = "ahash"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fcb51a0695d8f838b1ee009b3fbf66bda078cd64590202a864a8f3e8c4315c47"
+dependencies = [
+ "getrandom 0.2.3",
+ "once_cell",
+ "version_check",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "0.7.18"
@@ -1180,6 +1191,9 @@ name = "hashbrown"
 version = "0.11.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
+dependencies = [
+ "ahash",
+]
 
 [[package]]
 name = "heck"
@@ -1600,6 +1614,15 @@ dependencies = [
  "serde_json",
 ]
 
+[[package]]
+name = "lru"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c748cfe47cb8da225c37595b3108bea1c198c84aaae8ea0ba76d01dda9fc803"
+dependencies = [
+ "hashbrown",
+]
+
 [[package]]
 name = "lru-cache"
 version = "0.1.2"
@@ -2786,6 +2809,7 @@ dependencies = [
  "lettre",
  "linkify",
  "log",
+ "lru",
  "many-to-many",
  "mobc",
  "mobc-redis",