Remove CI status badge

[Torch3333]

Description

This removes the badge from the readme, showing the CI status for the master branch.

The badge was not working anymore since we stopped running the CI when commit were pushed to the master branch. This started a discussion about its usefulness, and we decided to remove it since showing the CI status of a development branch does not seem relevant.

Related issues and/or PRs

N/A

Changes made

Remove the CI status badge from the readme

Checklist

The following is a best-effort checklist. If any items in this checklist are not applicable to this PR or are dependent on other, unmerged PRs, please still mark the checkboxes after you have read and understood each item.

• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• Tests (unit, integration, etc.) have been added for the changes.
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

N/A

Release notes

N/A

[brfrn169]

LGTM! Thank you!

[komamitsu]

LGTM, thank you!