Fix YAML null value in fixture
The YAML null value is called `null` in YAML, not `Null`. yaml-rust
handles those values according to spec, so we should use the correct
capitalization.
See for more
information.
@@ -21,7 +21,7 @@ args:
about: tests positionals with exclusions
index: 2
default_value_if:
- - [flag, Null, some]
+ - [flag, null, some]
- [positional, other, something]
- flag:
short: f
