Fix parsing ordered lists that start at zero

Backported from 28fbb38

format/htmlparser.go

@@ -71,8 +71,13 @@ func (parser *HTMLParser) getAttribute(node *html.Node, attribute string) string
 	return ""
 }
 
-// Digits counts the number of digits in a non-negative integer.
+// Digits counts the number of digits (and the sign, if negative) in an integer.
 func Digits(num int) int {
+	if num == 0 {
+		return 1
+	} else if num < 0 {
+		return Digits(-num) + 1
+	}
 	return int(math.Floor(math.Log10(float64(num))) + 1)
 }
 

version.go

@@ -1,5 +1,5 @@
 package mautrix
 
-const Version = "v0.11.0"
+const Version = "v0.11.1"
 
 var DefaultUserAgent = "mautrix-go/" + Version