Log Message:
gallery-dl: Update net/gallery-dl to 1.0.2

Changes:
1.0.2
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* Added an option to set a custom user-agent string
* Improved retry behavior for failed HTTP requests
* Improved `seiga` by providing better metadata and getting more than the
  latest 200 images
* Improved `tumblr` by adding support for all post types, scanning for inline
  images and following external links] (#48)
* Fixed extraction issues for `hbrowse`, `khinsider` and `senmanga`