refactoring: extract symbol font version to constant
refactoring: extract symbol font version to constant

to make #11 a bit easier

geometalab/drf-utm-zone-info,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/drf-utm-zone-info,geometalab/osmaxx-frontend,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx