Update aws-sdk v2 examples -> v3

**Describe the bug**
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There are a few examples that use aws-sdk v2, however v2 is not included in new nodeJS on lambda...by default v3 is included.

It makes sense to update these examples to v3, since going forward most new functions will use aws-sdk v3.

**To Reproduce**
Steps to reproduce the behavior:
ie: Accessing the values in your function on the following page:
https://docs.amplify.aws/react/build-a-backend/functions/secrets/

**Expected behavior**
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**Screenshots**
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**Desktop (please complete the following information):**
- OS: [e.g. iOS]
- Browser [e.g. chrome, safari]
- Version [e.g. 22]

**Smartphone (please complete the following information):**
- Device: [e.g. iPhone6]
- OS: [e.g. iOS8.1]
- Browser [e.g. stock browser, safari]
- Version [e.g. 22]

**Additional context**
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