perf: use tokio

not sure how much this helps practically

Cargo.lock

@@ -1429,6 +1429,7 @@ dependencies = [
  "rayon",
  "rfd",
  "size",
+ "tokio",
  "zip",
 ]
 
@@ -1745,6 +1746,7 @@ dependencies = [
  "iced_core",
  "log",
  "rustc-hash 2.1.3",
+ "tokio",
  "wasm-bindgen-futures",
  "wasmtimer",
 ]
@@ -4259,6 +4261,15 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
 
+[[package]]
+name = "tokio"
+version = "1.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "202caea871b69668250d242070849eb495be178ed697a3e98aebce5bc81a0bed"
+dependencies = [
+ "pin-project-lite",
+]
+
 [[package]]
 name = "toml"
 version = "1.1.4+spec-1.1.0"