Fix for #210: Removed target attribute from some links.

[Nickatak]

Checklist

• My branch is up-to-date with the upstream predev branch.
• I have added necessary documentation (if appropriate).

Which issue does this PR fix?:
Fixes issue #210 (links undesirably opening in new tab).

This PR removes the target attribute entirely for each anchor tag mentioned in issue 210 inside /oshc/main/templates/base.html. To allow for consistency, I opted to completely remove the target attribute so that it matches other in-tab-opening links on the same page. This removal has been applied to the following links:

• Request a Session (under the Session drop-down of the nav-bar)
• Contests (on the nav-bar)
• Journey (in the footer, the flower-box emblem)

Why do we need this PR?:
UI/UX alteration to provide for favorable user interaction (altered links don't open in new tab when they don't need to).

Testing instructions:
I have taken the following steps, and am leaving them unchecked below for you to use:

• Create a virtual environment (and activate it)
• Clone the forked repository.
• Update to predev branch if you haven't [I don't know whether git saved that or not] (git fetch https://github.com/OpenSourceHelpCommunity/OpenSourceHelpCommunity.github.io/predev)
• Install pre-commit
• collectstatic (python manage.py collectstatic)
• Run development server (python manage.py runserver)
• Click on altered links in order to verify desired functionality.

TODOs (if any):
None

A picture of a cute animal (not mandatory but encouraged):
Old but good:

[coveralls]

Coverage remained the same at 72.269% when pulling 4cf4563 on Nickatak:predev into 850a09f on OpenSourceHelpCommunity:predev.

[tapaswenipathak]

🎉