[Build/CI] Upgrade jinja2 to get 3 moderate CVE fixes

[russellb]

Versions prior to 3.1.6 are vulnerable to these 3 CVEs. We should ensure
we are using >=3.1.6 to avoid any potential security vulnerability via
jinja2.

• GHSA-gmj6-6f8f-6699
• GHSA-q2x7-8rv6-6q7h
• GHSA-cpwx-vrp4-4pq7

Signed-off-by: Russell Bryant [email protected]

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