BUG: value_counts may raise OutOfBoundsDatetime
- [x] closes #13663
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry

The root cause looks normal `Index` raises `OutOfBoudsDatetime`. I think it should be coerced to `object` dtype because user specifies no dtype.

```
pd.Index([datetime(9999, 1, 1)])
# on current master
# OutOfBoundsDatetime: Out of bounds nanosecond timestamp: 9999-01-01 00:00:00

# this PR
Index([9999-01-01 00:00:00], dtype='object')
```
