libtracker-miners-common: Allow reading tracker-extract-3 executable
We need EXEC+READ permissions on the extractor executable, or the "tracker3 extract" CLI tool will fail trying to execute it with EACCES errors.
It is a bit of a mystery why we require this from the CLI tool, but tracker-miner-fs-3 can launch its private instance without issues. But let's roll with it.
Closes: #310 (closed)