Resolves an occasional glitch/flicker drawing the interface.
Regression in 405a5d3bd7ada5dd5af605b59ba07c7144f144a2
which removed shader unbinding when the batch is drawn.
GPU_shader_bind could running with the srgb uniform in an unexpected state.
To reproduce the bug, see: T86450#1154108 (I couldn't reproduce the steps in the original report).