Add SLR52, SLR53 and SLR54 to OpenSLR
Hi @lhoestq , I am not sure about the error message:
```
#!/bin/bash -eo pipefail
./scripts/datasets_metadata_validator.py
WARNING:root:❌ Failed to validate 'datasets/openslr/README.md':
__init__() got an unexpected keyword argument 'SLR32'
INFO:root:❌ Failed on 1 files.

Exited with code exit status 1
CircleCI received exit code 1 
```
Could you have a look please? Thanks. Hi ! The error is unrelated to your PR and has been fixed on master
Next time feel free to merge master into your branch to fix the CI error ;)
Add large speech datasets for Sinhala, Bengali and Nepali.