build!: drop Node 10 to support and update lastest Typescript

[summer-ji-eng]

Set Node v12 to minimum supported version

Drops Node 10 support, which has been EOL for about 1 year. 🦕

See: Google Cloud moves Cloud Client Libraries for Node.js support for version 10 to Maintenance

[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .kokoro/continuous/node10/common.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node10/docs.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node10/lint.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node10/test.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node8/common.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node8/test.cfg - .kokoro files are templated and should be updated in synthtool
• .github/workflows/ci.yaml - .github/workflows/ci.yaml (GitHub Actions) should be updated in synthtool

[summer-ji-eng]

@alexander-fenster I don't have access of setting to remove test(10) in gax-nodejs. Could you help me change to test(12). Thank you?

[alexander-fenster]

To remove node 10, change it here: https://github.com/googleapis/gax-nodejs/blob/main/.github/sync-repo-settings.yaml#L12, otherwise it will keep adding it. You can just send a separate PR to do it.

[sofisl]

I think we just need to update auth, thank you!

[summer-ji-eng]

I think we just need to update auth, thank you!

Upgraded. Thanks