fix: support L (liter) unit and number+unit denominator in Measure (#306)

- Add L → 升 to units_en.tsv
- Allow denominator in X/Y patterns to be measure (number+unit),
  not just bare unit. This enables 4.5L/100km → 每一百公里四点五升

Author: pengzhendong

tn/chinese/data/measure/units_en.tsv

@@ -41,6 +41,7 @@ kw	千瓦
 kW	千瓦
 lbs	磅
 lb	磅
+L	升
 m2	平方米
 m²	平方米
 m3	立方米

tn/chinese/rules/measure.py

@@ -58,7 +58,7 @@ def build_tagger(self):
 
         # 10km/h
         rmsign = rmspace + delete("/") + rmspace
-        tagger |= insert('numerator: "') + measure + rmsign + insert('" denominator: "') + units + insert('"')
+        tagger |= insert('numerator: "') + measure + rmsign + insert('" denominator: "') + (measure | units) + insert('"')
         self.tagger = self.add_tokens(tagger)
 
     def build_verbalizer(self):