chore(deps): update dependency cryptography to v3.4.8 (#156)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [cryptography](https://togithub.com/pyca/cryptography) | `==3.4.7` -> `==3.4.8` | [![age](https://badges.renovateapi.com/packages/pypi/cryptography/3.4.8/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/pypi/cryptography/3.4.8/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/pypi/cryptography/3.4.8/compatibility-slim/3.4.7)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/pypi/cryptography/3.4.8/confidence-slim/3.4.7)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>pyca/cryptography</summary>

### [`v3.4.8`](https://togithub.com/pyca/cryptography/compare/3.4.7...3.4.8)

[Compare Source](https://togithub.com/pyca/cryptography/compare/3.4.7...3.4.8)

</details>

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requirements.txt

@@ -1,5 +1,5 @@
 aiohttp==3.7.4.post0
-cryptography==3.4.7
+cryptography==3.4.8
 PyMySQL==1.0.2
 pg8000==1.21.0
 python-tds==1.11.0