fix(parser): fixed error messages for parsing

[aj3sh]

While parsing the datetime string, it shows the wrong message in some cases. This PR fixes the error message.

Case 1: Out of Range Date

npTime, err := nepalitime.Parse("1800-01-01", "%Y-%m-%d")
# Output: datetime string did not match with given format
# Expected: date is out of range

Case 2: Datetime string without year

npTime, err := nepalitime.Parse("01-01 %k", "%m-%d %%k");
# Output: datetime string did not match with given format
# Expected: unable to parse year

[aj3sh]

Ignore build codecov/patch