New ht thcovmat

Created by: achiefa

This is a follow-up of #1865, rebased from the current master.

requested review from @enocera

assigned to @enocera

added run-fit-bot label

Created by: github-actions[bot]

Greetings from your nice fit ! I have good news for you, I just finished my tasks:

• Fit Name: NNBOT-2ad60a7b9-2024-07-15
• Fit Report wrt master: https://vp.nnpdf.science/f0TNPeX3SlO5uwbJkr7I8Q==
• Fit Report wrt latest stable reference: https://vp.nnpdf.science/X6jx-wHfT5iJuz14nPatnQ==
• Fit Data: https://data.nnpdf.science/fits/NNBOT-2ad60a7b9-2024-07-15.tar.gz

Check the report carefully, and please buy me a , or better, a GPU !