add a gitcoin.co/explorer stale bounty filter

[owocki]

Description

Gitcoin.co/explorer lists out the all the bounties available at the moment
Many times there are bounties which get old and the funder loses track of them

The requirement is to add a filter similar to THIS in the My bounties section

In other words,
If a funder is logged in ->
they should be able to view bounties created by them more than 3 days but which are still in open state