add_belongs_to uses bigint in AlterTable statements (#224)

spec/migrator/alter_table_statement_spec.cr

@@ -76,10 +76,10 @@ describe Avram::Migrator::AlterTableStatement do
 
       built.statements.first.should eq <<-SQL
       ALTER TABLE comments
-        ADD user_id int NOT NULL REFERENCES users ON DELETE CASCADE,
-        ADD post_id int REFERENCES posts ON DELETE RESTRICT,
-        ADD category_label_id int NOT NULL REFERENCES custom_table ON DELETE SET NULL,
-        ADD employee_id int NOT NULL REFERENCES users ON DELETE CASCADE,
+        ADD user_id bigint NOT NULL REFERENCES users ON DELETE CASCADE,
+        ADD post_id bigint REFERENCES posts ON DELETE RESTRICT,
+        ADD category_label_id bigint NOT NULL REFERENCES custom_table ON DELETE SET NULL,
+        ADD employee_id bigint NOT NULL REFERENCES users ON DELETE CASCADE,
         ADD line_item_id uuid NOT NULL REFERENCES line_items ON DELETE CASCADE
       SQL
 

src/avram/migrator/alter_table_statement.cr

@@ -71,7 +71,7 @@ class Avram::Migrator::AlterTableStatement
   end
 
   # Adds a references column and index given a model class and references option.
-  macro add_belongs_to(type_declaration, on_delete, references = nil, foreign_key_type = Int32)
+  macro add_belongs_to(type_declaration, on_delete, references = nil, foreign_key_type = Int64)
     {% unless type_declaration.is_a?(TypeDeclaration) %}
       {% raise "add_belongs_to expected a type declaration like 'user : User', instead got: '#{type_declaration}'" %}
     {% end %}