forum: typing into search box and pressing enter should submit the search form

http://localhost/Code/BlueThrust5%20R17/BlueThrust5/src/forum/

<img width="383" alt="image" src="https://github.com/RedDragonWebDesign/BlueThrust5/assets/43397938/19d5375e-cbb8-4ce3-a3d2-5a85c3eebbfc">

Pressing enter currently does nothing.