remove unused serde feature from smol_str

Cargo.lock

@@ -1503,9 +1503,6 @@ name = "smol_str"
 version = "0.1.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b203e79e90905594272c1c97c7af701533d42adaab0beb3859018e477d54a3b0"
-dependencies = [
- "serde",
-]
 
 [[package]]
 name = "snap"
@@ -1572,7 +1569,6 @@ dependencies = [
  "rowan",
  "rustc-ap-rustc_lexer",
  "rustc-hash",
- "serde",
  "smol_str",
  "sourcegen",
  "stdx",

crates/syntax/Cargo.toml

@@ -18,8 +18,7 @@ rustc-hash = "1.1.0"
 arrayvec = "0.7"
 once_cell = "1.3.1"
 indexmap = "1.4.0"
-smol_str = { version = "0.1.15", features = ["serde"] }
-serde = { version = "1.0.106", features = ["derive"] }
+smol_str = "0.1.15"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 text_edit = { path = "../text_edit", version = "0.0.0" }

crates/tt/Cargo.toml

@@ -9,8 +9,6 @@ edition = "2018"
 doctest = false
 
 [dependencies]
-# ideally, `serde` should be enabled by `rust-analyzer`, but we enable it here
-# to reduce number of compilations
-smol_str = { version = "0.1.15", features = ["serde"] }
+smol_str = "0.1"
 
 stdx = { path = "../stdx", version = "0.0.0" }