vim-patch:8.2.0893: assert_equalfile() does not take a third argument

Problem:    Assert_equalfile() does not take a third argument.
Solution:   Implement the third argument. (Gary Johnson)
fb517bac23

src/nvim/eval.lua

@@ -28,7 +28,7 @@ return {
     asin={args=1, func="float_op_wrapper", data="&asin"},  -- WJMc
     assert_beeps={args={1, 2}},
     assert_equal={args={2, 3}},
-    assert_equalfile={args=2},
+    assert_equalfile={args={2, 3}},
     assert_exception={args={1, 2}},
     assert_fails={args={1, 3}},
     assert_false={args={1, 2}},