Remove unnecessary space because SPM can't read it

Remove unnecessary space, because SPM can't read it when fetching the package. Gives error suggesting to add swift tools version

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version: 5.7.0
+// swift-tools-version:5.7.0
 import PackageDescription
 
 let package = Package(