can't clear options - fixed

[krutarthjankat]

Fix #35

Hi, I am Krutarth Jankat, I have tried to fix the clear options issue by just filtering out empty strings at the time of submission. Please check if this is what was required

[benoit74]

LGTM

Some remark for next PR:

• you have to add Fix #xxx in your first comment (I did it for you) to link the PR with the corresponding issue (where xxx is the issue number, see https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue
• you must not commit your changes to a main branch but to a newly created branch (this will be especially important one we will give you developper permissions on this repo) ; the newly created branch should be name according to the intent of the changes, e.g. clear_flags

Please read https://github.com/openzim/overview/wiki/openZIM-code-contribution-workflow with a lot of attention to all details.

[benoit74]

And it would help if your PR title explains what the PR does, e.g. "Options / payload flags clearing", not what the original problem was.