Fix svg mime type allowing usage in themes
Fix svg mime type allowing usage in themes

fixes CNVS-38929

test plan:
- ensure that an svg file can be uploaded into the theme editor

Change-Id: I5c255c9707b26297d83b6b667143db4c6826ef51
Reviewed-on: https://gerrit.instructure.com/125830
Reviewed-by: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>
Product-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>
Tested-by: Jenkins
QA-Review: Tucker McKnight <4b51b98c1d84aa97854d216bd061ce5d3eda8a28@instructure.com>

sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms