Bump axios and @slack/webhook in /ops/functions

Bumps [axios](https://github.com/axios/axios) to 1.6.1 and updates ancestor dependency [@slack/webhook](https://github.com/slackapi/node-slack-sdk). These dependencies need to be updated together.


Updates `axios` from 0.21.4 to 1.6.1
- [Release notes](https://github.com/axios/axios/releases)
- [Changelog](https://github.com/axios/axios/blob/v1.x/CHANGELOG.md)
- [Commits](axios/axios@v0.21.4...v1.6.1)

Updates `@slack/webhook` from 6.1.0 to 7.0.1
- [Release notes](https://github.com/slackapi/node-slack-sdk/releases)
- [Commits](https://github.com/slackapi/node-slack-sdk/compare/@slack/[email protected]...@slack/[email protected])

---
updated-dependencies:
- dependency-name: axios
  dependency-type: indirect
- dependency-name: "@slack/webhook"
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

ops/functions/package.json

@@ -2,7 +2,7 @@
   "main": "index.js",
   "dependencies": {
     "@google-cloud/functions-framework": "^3.1.2",
-    "@slack/webhook": "^6.1.0",
+    "@slack/webhook": "^7.0.1",
     "body-parser": "^1.20.0",
     "json5": "^2.2.1"
   },