enable r2d2 feature in diesel

Cargo.lock

@@ -263,6 +263,7 @@ dependencies = [
  "diesel_derives",
  "itoa",
  "pq-sys",
+ "r2d2",
 ]
 
 [[package]]
@@ -1304,6 +1305,17 @@ version = "5.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "74765f6d916ee2faa39bc8e68e4f3ed8949b48cccdac59983d287a7cb71ce9c5"
 
+[[package]]
+name = "r2d2"
+version = "0.8.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51de85fb3fb6524929c8a2eb85e6b6d363de4e8c48f9e2c2eac4944abc181c93"
+dependencies = [
+ "log",
+ "parking_lot",
+ "scheduled-thread-pool",
+]
+
 [[package]]
 name = "rand"
 version = "0.9.0"
@@ -1459,6 +1471,15 @@ dependencies = [
  "windows-sys 0.59.0",
 ]
 
+[[package]]
+name = "scheduled-thread-pool"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3cbc66816425a074528352f5789333ecff06ca41b36b0b0efdfbb29edc391a19"
+dependencies = [
+ "parking_lot",
+]
+
 [[package]]
 name = "scoped-futures"
 version = "0.1.4"

Cargo.toml

@@ -6,7 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-diesel = { version = "2.2.8", features = ["postgres"] }
+diesel = { version = "2.2.8", features = ["postgres", "r2d2"] }
 diesel-async = { version = "0.5.2", features = ["postgres"] }
 dotenvy = "0.15.7"
 envconfig = "0.11.0"