Bump aiohttp in /libraries/botbuilder-integration-aiohttp (#1552)

Bumps [aiohttp](https://github.com/aio-libs/aiohttp) from 3.6.2 to 3.7.4.
- [Release notes](https://github.com/aio-libs/aiohttp/releases)
- [Changelog](https://github.com/aio-libs/aiohttp/blob/master/CHANGES.rst)
- [Commits](aio-libs/aiohttp@v3.6.2...v3.7.4)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: tracyboehrer <tracyboehrer@users.noreply.github.com>
Co-authored-by: Axel Suárez <axsuarez@microsoft.com>

Author: 3 people

libraries/botbuilder-integration-aiohttp/requirements.txt

@@ -1,4 +1,4 @@
 msrest==0.6.10
 botframework-connector==4.13.0
 botbuilder-schema==4.13.0
-aiohttp==3.6.2
+aiohttp==3.7.4