Replace bare excepts by explicit excepts in pandas/io/
(superseeds #18419, same task for different files: #22872, #22873, #22874, #22877)

In several parts of the code, we have bare excepts in the form of:
```python
try:
    my_value = my_dict[my_key]
except:  # we are capturing all the exceptions, when we want to capture only KeyError
    my_value = None
```

This is a bad practice, and we want to avoid having this in the code. What we want instead is:
```python
try:
    my_value = my_dict[my_key]
except KeyError:
    my_value = None
```
Of course in every case, the exception can be different (not always `KeyError`), and some research is needed to see which is the right exception (or exceptions, it can be a tuple) that needs to be captured. In some cases, every exception needs to be captured and we'll use `except Exception:`, but this should be avoided unless we really need to capture all exceptions.

This issue is to fix all the bare excepts in testing files `pandas/tests/`. At the moment they are (note that the list can change as code evolves):
```
pandas/io/clipboards.py:45:9: E722 do not use bare except'
pandas/io/packers.py:706:13: E722 do not use bare except'
pandas/io/parsers.py:1811:9: E722 do not use bare except'
pandas/io/parsers.py:3037:13: E722 do not use bare except'
pandas/io/parsers.py:3266:9: E722 do not use bare except'
pandas/io/parsers.py:3287:9: E722 do not use bare except'
pandas/io/parsers.py:3291:9: E722 do not use bare except'
pandas/io/pickle.py:172:13: E722 do not use bare except'
pandas/io/pickle.py:177:5: E722 do not use bare except'
pandas/io/sql.py:385:5: E722 do not use bare except'
pandas/io/sql.py:850:13: E722 do not use bare except'
pandas/io/sql.py:1363:9: E722 do not use bare except'
pandas/io/stata.py:1255:9: E722 do not use bare except'
pandas/io/stata.py:1260:9: E722 do not use bare except'
pandas/io/formats/console.py:103:5: E722 do not use bare except'
pandas/io/formats/console.py:121:5: E722 do not use bare except'
pandas/io/formats/console.py:140:5: E722 do not use bare except'
pandas/io/formats/console.py:152:5: E722 do not use bare except'
pandas/io/formats/terminal.py:81:5: E722 do not use bare except'
pandas/io/formats/terminal.py:111:5: E722 do not use bare except'
pandas/io/formats/terminal.py:123:9: E722 do not use bare except'
pandas/io/formats/terminal.py:132:9: E722 do not use bare except'
pandas/io/formats/terminal.py:138:9: E722 do not use bare except'
pandas/io/sas/sasreader.py:49:9: E722 do not use bare except'
pandas/io/sas/sas_xport.py:249:13: E722 do not use bare except'
```
An updated list can be obtained by running: `flake8 --select=E722 --config=none --exclude=pandas/io/pytables/ pandas/io`