Remove unused git-commit-dark icon

Hopefully git icons will be here soon, this is unused so might as well
just remove it.
Signed-off-by: Waqar Ahmed <waqar.17a@gmail.com>

addons/project/icons/git-commit-dark.svg

-<svg xmlns="http://www.w3.org/2000/svg" width="20" height="10"><rect id="backgroundrect" width="100%" height="100%" x="0" y="0" fill="none" stroke="none" style="" class=""/><g class="currentLayer" style=""><title>Layer 1</title><path fill-rule="evenodd" d="M13.5,4.99809455871582 a3.5,3.5 0 1 1 -7,0 a3.5,3.5 0 0 1 7,0 zm1.444000005722046,-0.75 a5.000999927520752,5.000999927520752 0 0 0 -9.887999534606934,0 H0.75 a0.75,0.75 0 1 0 0,1.5 h4.306000232696533 a5.000999927520752,5.000999927520752 0 0 0 9.887999534606934,0 h4.306000232696533 a0.75,0.75 0 1 0 0,-1.5 h-4.306000232696533 z" id="svg_1" class="selected" fill="#ffffff" fill-opacity="1"/></g></svg>
\ No newline at end of file

addons/project/plugin.qrc

@@ -3,7 +3,6 @@
         <file>ui.rc</file>
     </qresource>
     <qresource prefix="/icons">
-        <file>icons/git-commit-dark.svg</file>
         <file>icons/sc-apps-git.svg</file>
     </qresource>
 </RCC>