Allow : in bundle names

[Natureshadow]

This is needed e.g. for rollup-plugin-virtual, which prefixes bundle names with virtual:.

Relevant standard: https://www.rfc-editor.org/rfc/rfc3986#section-4.2

A path segment that contains a colon character (e.g., "this:that")
cannot be used as the first segment of a relative-path reference, as
it would be mistaken for a scheme name. Such a segment must be
preceded by a dot-segment (e.g., "./this:that") to make a relative-
path reference.

[Natureshadow]

@MrBin99 A timely merge and release to PyPI would be most appreciated!