Replace regex with pattern as string to support OTP 28

OTP 28 changes the implementation of the regex module, and as a
result you can no longer use regexes as module attributes.

By changing the regex to a pattern as a string it can still be
used in the error message, and just needs to be compiled before
usage.

Author: TBK145

lib/absinthe/phase/schema/validation/names_must_be_valid.ex

@@ -4,7 +4,7 @@ defmodule Absinthe.Phase.Schema.Validation.NamesMustBeValid do
   use Absinthe.Phase
   alias Absinthe.Blueprint
 
-  @valid_name_regex ~r/^[_A-Za-z][_0-9A-Za-z]*$/
+  @valid_name_regex "^[_A-Za-z][_0-9A-Za-z]*$"
 
   def run(bp, _) do
     bp = Blueprint.prewalk(bp, &validate_names/1)
@@ -30,7 +30,9 @@ defmodule Absinthe.Phase.Schema.Validation.NamesMustBeValid do
   end
 
   defp valid_name?(name) do
-    Regex.match?(@valid_name_regex, name)
+    @valid_name_regex
+    |> Regex.compile!()
+    |> Regex.match?(name)
   end
 
   defp error(object, data) do
@@ -43,7 +45,7 @@ defmodule Absinthe.Phase.Schema.Validation.NamesMustBeValid do
   end
 
   @description """
-  Name does not match possible #{inspect(@valid_name_regex)} regex.
+  Name does not match possible #{@valid_name_regex} regex.
 
   > Names in GraphQL are limited to this ASCII subset of possible characters to
   > support interoperation with as many other systems as possible.