chore: make credential dependencies platform-specific

Author: weihanglo

credential/cargo-credential-macos-keychain/Cargo.toml

@@ -8,4 +8,6 @@ description = "A Cargo credential process that stores tokens in a macOS keychain
 
 [dependencies]
 cargo-credential = { version = "0.2.0", path = "../cargo-credential" }
+
+[target.'cfg(target_os = "macos")'.dependencies]
 security-framework = "2.0.0"

credential/cargo-credential-wincred/Cargo.toml

@@ -8,4 +8,10 @@ description = "A Cargo credential process that stores tokens with Windows Creden
 
 [dependencies]
 cargo-credential = { version = "0.2.0", path = "../cargo-credential" }
-windows-sys = { version = "0.48", features = ["Win32_Foundation", "Win32_Security_Credentials"] }
+
+[target.'cfg(windows)'.dependencies.windows-sys]
+version = "0.48"
+features = [
+  "Win32_Foundation",
+  "Win32_Security_Credentials"
+]