Hi en fixes

[mayuris-00]

What does this PR do ?

Three small fixes to the Hindi ITN grammar, plus hi_en test coverage.

• measurements.tsv: 8 rows for per-unit measures (m/s, km/s, m/min, kg/h, L/s, ns).
  The table already had मील प्रति सेकंड and मील प्रति घंटा but not the metre,
  kilogram or litre equivalents, so the unit converted while प्रति X stayed as words.
• whitelist.tsv: 4 honorifics (प्रो., इंजी., पं., स्व.). The table held 7 entries.
• time.py: accept शून्य as an hour. Hours were composed through range(1, 25) and
  graph_digit covers only १ to ९, so शून्य बजकर तीस मिनट could not parse as a time
  and fell to the measure grammar as ० बजकर ३० m. Now returns ०:३०.

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• New Feature
• Bugfix
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