Cleanup: GPU: Fix warning

Referenced by issue #77752, AMD Pro Driver crashes on ASAN build when switching to edit mode

source/blender/gpu/intern/gpu_texture.c

@@ -1637,6 +1637,7 @@ void GPU_texture_clear(GPUTexture *tex, eGPUDataFormat gpu_data_format, const vo
         }
         default:
           BLI_assert(!"Unhandled data format");
+          depth = 0.0f;
           break;
       }
       glClearDepth(depth);