Fix OAuth apps page crashing when listing apps with certain admin API scopes (#25713)

app/lib/scope_parser.rb

 # frozen_string_literal: true
 
 class ScopeParser < Parslet::Parser
-  rule(:term)      { match('[a-z]').repeat(1).as(:term) }
+  rule(:term)      { match('[a-z_]').repeat(1).as(:term) }
   rule(:colon)     { str(':') }
   rule(:access)    { (str('write') | str('read')).as(:access) }
   rule(:namespace) { str('admin').as(:namespace) }