BUG: Failing clipboard tests
- [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.

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

---

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

```python
# Your code here
>>> pd.__version__
'1.1.0.dev0+1655.g1132aba3e'

pytest pandas/tests/io/test_clipboard.py
```

#### Problem description

Final three tests fail. Looks like the test is designed for Windows, I'm running a Mac. The test references [PR#25040](https://github.com/pandas-dev/pandas/pull/25040)

**EDIT:**  Just realized I'm actually running it in a Docker container. From Pyperclip documentation, looks like I need either gtk or PyQt4 (for Linux) or pbcopy and pbpaste (for Mac) installed. I suppose that should be included as a dependency in the Dockerfile?