Update host_darwin.go

Copy+pasta got me again! 🍝

No new variable on the left of `:=` 😂

host/host_darwin.go

@@ -190,7 +190,7 @@ func PlatformInformationWithContext(ctx context.Context) (string, string, string
 	}
 
 	// check if the macos server version file exists
-	_, err := os.Stat("/System/Library/CoreServices/ServerVersion.plist")
+	_, err = os.Stat("/System/Library/CoreServices/ServerVersion.plist")
 
 	// server file doesn't exist
 	if os.IsNotExist(err) {