Ignore test results in .gitignore

[nyurik]

After running cargo test, lots of new untracked files are being created. They should be listed in the .gitignore, but it seems like they are nearly identical to the ones already checked in into the same git location. I think they should be cleaned up and listed in .gitignore, but I am not certain what is the desired wildcard is, so filing it as an issue instead.

        lib/oxigraph/tests/rocksdb_bc_data/000032.sst
        lib/oxigraph/tests/rocksdb_bc_data/000033.sst
        lib/oxigraph/tests/rocksdb_bc_data/000034.sst
        lib/oxigraph/tests/rocksdb_bc_data/000035.sst
        lib/oxigraph/tests/rocksdb_bc_data/000036.sst
        lib/oxigraph/tests/rocksdb_bc_data/000037.sst
        lib/oxigraph/tests/rocksdb_bc_data/000066.sst
        lib/oxigraph/tests/rocksdb_bc_data/000067.sst
        lib/oxigraph/tests/rocksdb_bc_data/000068.sst
        lib/oxigraph/tests/rocksdb_bc_data/000069.log
        lib/oxigraph/tests/rocksdb_bc_data/000070.sst
        lib/oxigraph/tests/rocksdb_bc_data/000071.sst
        lib/oxigraph/tests/rocksdb_bc_data/000072.sst
        lib/oxigraph/tests/rocksdb_bc_data/000075.log
        lib/oxigraph/tests/rocksdb_bc_data/000103.sst
        lib/oxigraph/tests/rocksdb_bc_data/210901102448970116524957277514017033403
        lib/oxigraph/tests/rocksdb_bc_data/LOG
        lib/oxigraph/tests/rocksdb_bc_data/LOG.old.1707432370940434
        lib/oxigraph/tests/rocksdb_bc_data/MANIFEST-000076
        lib/oxigraph/tests/rocksdb_bc_data/OPTIONS-000100
        lib/oxigraph/tests/rocksdb_bc_data/OPTIONS-000102