Fixed deprecations for rails 6.1 and 6.2

test/models/mat_test.rb

@@ -8,6 +8,6 @@ class MatTest < ActiveSupport::TestCase
    test "Mat validations" do
       mat = Mat.new
       assert_not mat.valid?
-      assert_equal [:name], mat.errors.keys
+      assert_equal [:name], mat.errors.attribute_names
     end
 end

test/models/school_test.rb

@@ -8,6 +8,6 @@ class SchoolTest < ActiveSupport::TestCase
    test "School validations" do
       school = School.new
       assert_not school.valid?
-      assert_equal [:name], school.errors.keys
+      assert_equal [:name], school.errors.attribute_names
     end
 end

test/models/tournament_test.rb

@@ -9,6 +9,6 @@ class TournamentTest < ActiveSupport::TestCase
    test "Tournament validations" do
       tourney = Tournament.new
       assert_not tourney.valid?
-      assert_equal [:date, :name, :tournament_type, :address, :director, :director_email], tourney.errors.keys
+      assert_equal [:date, :name, :tournament_type, :address, :director, :director_email], tourney.errors.attribute_names
     end
 end

test/models/weight_test.rb

@@ -8,6 +8,6 @@ class WeightTest < ActiveSupport::TestCase
    test "Weight validations" do
       weight = Weight.new
       assert_not weight.valid?
-      assert_equal [:max], weight.errors.keys
+      assert_equal [:max], weight.errors.attribute_names
     end
 end

test/models/wrestler_test.rb

@@ -8,6 +8,6 @@ class WrestlerTest < ActiveSupport::TestCase
    test "Wrestler validations" do
       wrestler = Wrestler.new
       assert_not wrestler.valid?
-      assert_equal [:name, :weight_id, :school_id], wrestler.errors.keys
+      assert_equal [:name, :weight_id, :school_id], wrestler.errors.attribute_names
     end
 end