v0.12.0

What's Changed

• Deal with metadataheader not being present by @Florisklooster in #213
• Accept files with extension XML as well by @MattBrst in #216
• Fix for #218 by @OnnoEbbens in #219
• Fix issue 208 by @rubencalje in #217
• 210 indexing obscollection always returns obs column by @OnnoEbbens in #220
• Release 0.12.0 by @OnnoEbbens in #221

Full Changelog: v0.11.3...v0.12.0