Update enum_to_i: test equality with integer

Demonstrates kaitai-io/kaitai_struct#802

Author: generalmimon

formats/enum_to_i.ksy

@@ -20,3 +20,7 @@ instances:
     value: pet_1.to_i + 0x8000
   one_lt_two:
     value: pet_1.to_i < pet_2.to_i
+  pet_1_eq_int:
+    value: pet_1.to_i == 7
+  pet_2_eq_int:
+    value: pet_2.to_i == 5

spec/ks/enum_to_i.kst

@@ -12,3 +12,7 @@ asserts:
     expected: 0x8007
   - actual: one_lt_two
     expected: true
+  - actual: pet_1_eq_int
+    expected: true
+  - actual: pet_2_eq_int
+    expected: false