Add CI for pull requests

[Tmonster]

Here is a workflow that should run whenever a pull request is created. For some reason it doesn't anymore. Might be to do with the workflow dispatch parameter. It should also be similar to the workflow file in the duckdb-fuzzer-ci repository. Maybe we could also have a CI job that checks that the two files always stay the same? Theoretically I think you can just rip the GitHub actions file form the duckdb-fuzzer-ci