Adding metadata tag to non rendered tags

[ldevillez]

Description

Metadata is a valid svg tag but it should not be directly rendered.

Fixes #141

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Tested with the svg from #141. The tikz output is similar to the svg.

Checklist:

• My code follows the style guidelines of this project (black/pylint)
• I have updated the changelog with the corresponding changes
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[bchardin]

Thanks for the fix. The test from #141 now also works for me.