lal_refactor-extract_variable: Add qualified Ada_Op'(Node.As_Bin_Op.F_Op)

[andrewathalye]

Applying the attached patch to lal_refactor-extract_variable.adb resolves an error "selecting expression of general case statement is ambiguous" when trying to compile the file.

diff --git a/src/lal_refactor-extract_variable.adb b/src/lal_refactor-extract_variable.adb.new
index 2a3c256..49533d0 100644
--- a/src/lal_refactor-extract_variable.adb
+++ b/src/lal_refactor-extract_variable.adb.new
@@ -77,7 +77,7 @@ package body LAL_Refactor.Extract_Variable is
 
          function Get_Priority (Node : Ada_Node) return Natural is
          begin
-            case Node.As_Bin_Op.F_Op is
+            case Ada_Op'(Node.As_Bin_Op.F_Op) is
                when Ada_Op_In | Ada_Op_Not_In =>
                   return 7;