Create LeakSanitizer suppression rules to run with detect_leaks=1

Hi,

Atheris is currently recommended to run with ASan's `detect_leaks=0` as per [native_extension_fuzzing.md#leak-detection](https://github.com/google/atheris/blob/33a1322dadaf4d561f7c99b5641cb33748d4036c/native_extension_fuzzing.md#leak-detection).

I believe this can be fixed/changed by suppressing the Python initialization's memory leaks using the [LeakSanitizer suppression rules](https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer#suppressions).

We should implement those rules and recommend users to run with them, or, make them somehow "builtin" (so they are applied automagically) if there is such an option.