Add PeMS traffic dataset

[WenjieDu]

1. Dataset description

https://github.com/laiguokun/multivariate-time-series-data/tree/master?tab=readme-ov-file#traffic-usage

The raw data is in http://pems.dot.ca.gov/. The data in this repo is a collection of 48 months (2015-2016) hourly data from the California Department of Transportation. The data describes the road occupancy rates (between 0 and 1) measured by different sensors on San Francisco Bay area freeways.

2. Check open-source status

• The dataset implementation is publicly available

3. Provide useful information for the implementation

https://pems.dot.ca.gov