v3.0.3

• Fixed handling of never-matching empty attr selectors: [att^=""], [att$=""], [att*=""]
• Fixed Attribute::value_source_location() returning a bogus span for attributes written
  without a value (e.g. <div hidden>): it now returns None for them. Previously it
  returned a zero-length span pointing at the start of the parser's current buffer — or
  None, depending on where the tag fell relative to a write() boundary — and in the
  None case name_source_location() was also absent. Attribute source locations no
  longer depend on how the input was chunked.
• Made memory limit stricter for attributes.
• Improved performance of deeply nested end tag handlers.