Bump axios and @microsoft/sp-build-web in /samples/react-calendar

Removes [axios](https://github.com/axios/axios). It's no longer used after updating ancestor dependency [@microsoft/sp-build-web](http://aka.ms/spfx). These dependencies need to be updated together.


Removes `axios`

Updates `@microsoft/sp-build-web` from 1.12.1 to 1.20.1

---
updated-dependencies:
- dependency-name: axios
  dependency-type: indirect
- dependency-name: "@microsoft/sp-build-web"
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

samples/react-calendar/package.json

@@ -52,7 +52,7 @@
   },
   "devDependencies": {
     "@microsoft/rush-stack-compiler-3.9": "0.4.47",
-    "@microsoft/sp-build-web": "1.12.1",
+    "@microsoft/sp-build-web": "1.20.1",
     "@microsoft/sp-module-interfaces": "1.12.1",
     "@microsoft/sp-tslint-rules": "1.12.1",
     "@microsoft/sp-webpart-workbench": "1.12.1",