Remove restriction on the project's package name

There are restrictions regarding how modules are called, but given that packages are tight to repositories anyway; there's no way someone can publish and use an aiken package on 'aiken-lang' without being part of the organization. So the restriction on the command-line is pointless. Plus, it prevents us from using 'aiken-lang' as a placeholder name for tutorials.

crates/aiken/src/cmd/new.rs

@@ -29,8 +29,6 @@ pub fn exec(args: Args) -> miette::Result<()> {
 }
 
 fn create_project(args: Args, package_name: &PackageName) -> miette::Result<()> {
-    package_name.restrict().into_diagnostic()?;
-
     let root = PathBuf::from(&package_name.repo);
 
     if root.exists() {