BUG: read_sql parse_dates does not allow for "errors" arg
- [x] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the latest version of pandas.

- [ ] (optional) I have confirmed this bug exists on the master branch of pandas.

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**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

#### Code Sample, a copy-pastable example

```python
# Your code here
import pandas

query = ...
connection = ...
parse_dates_dict = {'column_name': {'errors': 'coerce'}}
pandas.read_sql(query, parse_dates=parse_dates_dict)
```

#### Problem description

According to the api for [read_sql](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.read_sql.html), the `parse_date` argument should be able to contain a dict of dicts with kwargs per column to be passed along to `pandas.to_datetime()`, as shown in the example above.

However, this will result in the error:
`TypeError: to_datetime() got multiple values for keyword argument 'errors'`

This is because of [this line of code:](https://github.com/pandas-dev/pandas/blob/v1.0.5/pandas/io/sql.py#L81)
`return to_datetime(col, errors="ignore", **format)` - where `format` is our kwargs from that specific column.
Specifically, the hardcoded `errors` argument collides with the passed kwarg.

It seems like the `errors` argument cannot be overridden by kwargs in this implementation.

#### Expected Output

Expect `errors` arg in to be overridden by the kwargs argument, or that the documentation explicitly says that it cannot be overridden for some reason.

