v1.3.8

What's Changed

• Format numbers per the XPath 1.0 string() rules by @gaoflow in #125
• Fix remaining XPath comparison coercion edge cases by @floze-the-genius in #127
• fix: round() and mod follow the XPath 1.0 numeric spec by @gaoflow in #128
• Reject undeclared variables nested in an expression by @AruneshDwivedi in #129
• parse: '' is not a name character (§3.7) — fix nameexpr lexing (#126) by @alonsoalpizar in #130