CI: unpin pymysql, sync min version, and skip failing test
xref #36465


thanks @fangchenli  hmm

> FAILED pandas/tests/io/test_sql.py::TestMySQLAlchemy::test_to_sql_with_negative_npinf[load_iris_data0-input2]
FAILED pandas/tests/io/test_sql.py::TestMySQLAlchemyConn::test_to_sql_with_negative_npinf[load_iris_data0-input2]

on the database build When one column is `infe0`, df that contains `np.nan` actually could be converted to SQL table. That's why we don't catch any error.

```python
import pandas
import numpy

from sqlalchemy import create_engine

engine = create_engine('mysql+pymysql://root:@localhost/foobar')

table = "foobar"
pandas.DataFrame({'foo': [-numpy.inf, 3], 'infe0': ['bar', 3]}).to_sql(table, engine, index=False)
import pandas.io.sql as sql
res = sql.read_sql_table(table, engine)
print(res)
```

```bash
   foo infe0
0  NaN   bar
1  3.0     3
```

But that column name must be `infe0`. I'm not sure why it's special.

 thanks @fangchenli 