chore(deps): update dependency jinja2 to v3 (#878)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [jinja2](https://palletsprojects.com/p/jinja/) ([changelog](https://jinja.palletsprojects.com/changes/)) | `==2.11.3` -> `==3.0.0` | [![age](https://badges.renovateapi.com/packages/pypi/jinja2/3.0.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/pypi/jinja2/3.0.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/pypi/jinja2/3.0.0/compatibility-slim/2.11.3)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/pypi/jinja2/3.0.0/confidence-slim/2.11.3)](https://docs.renovatebot.com/merge-confidence/) |

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packages/gapic-generator/requirements.txt

@@ -1,7 +1,7 @@
 click==7.1.2
 google-api-core==1.26.3
 googleapis-common-protos==1.53.0
-jinja2==2.11.3
+jinja2==3.0.0
 MarkupSafe==2.0.0
 protobuf==3.16.0
 pypandoc==1.5