[patch]: gate crypto

Package.swift

@@ -2,6 +2,16 @@
 import PackageDescription
 import CompilerPluginSupport
 
+var Cryptography: String { "Cryptography" }
+
+var enabledTraits: Set<String>
+
+#if os(Linux)
+enabledTraits = [Cryptography]
+#else
+enabledTraits = []
+#endif
+
 let package: Package = .init(
     name: "swift-github",
     platforms: [.macOS(.v15), .iOS(.v18), .tvOS(.v18), .watchOS(.v11), .visionOS(.v2)],
@@ -11,6 +21,10 @@ let package: Package = .init(
         .library(name: "GitHubRSA", targets: ["GitHubRSA"]),
         .library(name: "SHA1_JSON", targets: ["SHA1_JSON"]),
     ],
+    traits: [
+        .trait(name: Cryptography),
+        .default(enabledTraits: enabledTraits),
+    ],
     dependencies: [
         .package(url: "https://github.com/ordo-one/dollup", from: "1.0.1"),
 
@@ -44,10 +58,14 @@ let package: Package = .init(
             name: "GitHubRSA",
             dependencies: [
                 .target(name: "GitHubAPI"),
-
-                .product(name: "Cryptography", package: "swift-cryptography"),
+                .product(
+                    name: "Cryptography",
+                    package: "swift-cryptography",
+                    condition: .when(traits: [Cryptography])
+                ),
                 .product(name: "JWT", package: "swift-jwt"),
-            ]
+            ],
+
         ),
 
         .target(

Sources/GitHubRSA/RSA.PrivateKey (ext).swift

@@ -1,3 +1,4 @@
+#if canImport(Cryptography)
 public import GitHubAPI
 public import Cryptography
 import JSON
@@ -10,3 +11,4 @@ extension RSA.PrivateKey {
         }
     }
 }
+#endif