Add scorecard to powsybl-diagram

[So-Fras]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines

Does this PR already have an issue describing the problem?
No

What kind of change does this PR introduce?
This PR adds another GitHub action (Scorecard) to the powsybl-diagram workflow

Does this PR introduce a breaking change or deprecate an API?

• Yes
• No

[sonarcloud]

Quality Gate passed

Issues
0 New issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[So-Fras]

I tried to create a fine-grained PAT as described here.
It seems to me that we may need it because we use branch protection rules.
However, I cannot go through the "select the powsybl-diagram repository" step (I think it is because I am not an owner of the repository).