Remove sendability warnings

Modifications:

* change hardcoded `UInt8` characters to `let`
* make `MemcachedFlags` `Sendable`
* make `TimeToLive` `Sendable`
* make `MemcachedRequest` `Sendable`

Author: felixschlegel

Sources/SwiftMemcache/Extensions/UInt8+Characters.swift

@@ -13,20 +13,20 @@
 //===----------------------------------------------------------------------===//
 
 extension UInt8 {
-    static var whitespace: UInt8 = .init(ascii: " ")
-    static var newline: UInt8 = .init(ascii: "\n")
-    static var carriageReturn: UInt8 = .init(ascii: "\r")
-    static var m: UInt8 = .init(ascii: "m")
-    static var s: UInt8 = .init(ascii: "s")
-    static var g: UInt8 = .init(ascii: "g")
-    static var d: UInt8 = .init(ascii: "d")
-    static var v: UInt8 = .init(ascii: "v")
-    static var T: UInt8 = .init(ascii: "T")
-    static var M: UInt8 = .init(ascii: "M")
-    static var P: UInt8 = .init(ascii: "P")
-    static var A: UInt8 = .init(ascii: "A")
-    static var E: UInt8 = .init(ascii: "E")
-    static var R: UInt8 = .init(ascii: "R")
-    static var zero: UInt8 = .init(ascii: "0")
-    static var nine: UInt8 = .init(ascii: "9")
+    static let whitespace: UInt8 = .init(ascii: " ")
+    static let newline: UInt8 = .init(ascii: "\n")
+    static let carriageReturn: UInt8 = .init(ascii: "\r")
+    static let m: UInt8 = .init(ascii: "m")
+    static let s: UInt8 = .init(ascii: "s")
+    static let g: UInt8 = .init(ascii: "g")
+    static let d: UInt8 = .init(ascii: "d")
+    static let v: UInt8 = .init(ascii: "v")
+    static let T: UInt8 = .init(ascii: "T")
+    static let M: UInt8 = .init(ascii: "M")
+    static let P: UInt8 = .init(ascii: "P")
+    static let A: UInt8 = .init(ascii: "A")
+    static let E: UInt8 = .init(ascii: "E")
+    static let R: UInt8 = .init(ascii: "R")
+    static let zero: UInt8 = .init(ascii: "0")
+    static let nine: UInt8 = .init(ascii: "9")
 }

Sources/SwiftMemcache/MemcachedFlags.swift

@@ -18,7 +18,7 @@
 /// The 'v' flag for the meta get command dictates whether the item value should be returned in the data block.
 /// The 'T' flag is used for both the meta get and meta set commands to specify the Time-To-Live (TTL) for an item.
 /// The 't' flag for the meta get command indicates whether the Time-To-Live (TTL) for the item should be returned.
-struct MemcachedFlags {
+struct MemcachedFlags: Sendable {
     /// Flag 'v' for the 'mg' (meta get) command.
     ///
     /// If true, the item value is returned in the data block.
@@ -41,7 +41,7 @@ struct MemcachedFlags {
 }
 
 /// Enum representing the Time-To-Live (TTL) of a Memcached value.
-public enum TimeToLive: Equatable, Hashable {
+public enum TimeToLive: Sendable, Equatable, Hashable {
     /// The value should never expire.
     case indefinitely
     /// The value should expire after a specified time.

Sources/SwiftMemcache/MemcachedRequest.swift

@@ -13,19 +13,19 @@
 //===----------------------------------------------------------------------===//
 
 import NIOCore
-enum MemcachedRequest {
-    struct SetCommand {
+enum MemcachedRequest: Sendable {
+    struct SetCommand: Sendable {
         let key: String
         var value: ByteBuffer
         var flags: MemcachedFlags?
     }
 
-    struct GetCommand {
+    struct GetCommand: Sendable {
         let key: String
         var flags: MemcachedFlags
     }
 
-    struct DeleteCommand {
+    struct DeleteCommand: Sendable {
         let key: String
     }