Check license of top-level dependencies for all integrations

[julian-risch]

Is your feature request related to a problem? Please describe.
Similar to the license compliance workflow in Haystack core, we should check the license of top-level dependencies in haystack-core-integrations.
Here is the workflow in Haystack: https://github.com/deepset-ai/haystack/blob/1d4883f1789dd281f0a3de00854ec547bfb19213/.github/workflows/license_compliance.yml#L49
The result of the top-level dependency check could be shown for each integration in the inventory table in the readme of the repo.

Describe the solution you'd like

• Add a license check workflow that is similar to the one we use in Haystack.
• Merging all dependencies into one long list and doing only a single check instead of one check per integration

Describe alternatives you've considered
Not adding the checks, which poses legal risks and adoption risks.

Additional context
We should check with @ArzelaAscoIi if he can help. We should also check how to connect this with FOSSA. It's different than Haystack core because haystack-core-integrations has the code for multiple pypi packages in one repo.