BUG: Unexpected period range index shift
### 

- [X] I have checked that this issue has not already been reported.

- [X] I have confirmed this bug exists on the [latest version](https://pandas.pydata.org/docs/whatsnew/index.html) of pandas.

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


### Reproducible Example

```python
import pandas as pd
from datetime import datetime
print(pd.__version__)
df = pd.DataFrame(range(24))
df.index = pd.period_range(datetime(1900,1,1), periods=24, freq="1H")
resamp = df.resample("6H",label='right', closed='right').sum()
```


### Issue Description

Resampling a df that has a period range index results in an unexpected temporal shift in the results in the pandas version 1.3.4. This can be seen by running the example code in version 1.3.4 and comparing the results to version 1.0.5.

### Expected Behavior

Running the example code in version 1.0.5 results in the expected behavior.

### Installed Versions

1.3.4
