chore(ci): switch to next-gen CircleCI's convenience images

[bednar]

Proposed Changes

The current images are deprecated and no longer supported:

• https://discuss.circleci.com/t/legacy-convenience-image-deprecation/41034?mkt_tok=NDg1LVpNSC02MjYAAAF_aZ4aQBMMtwIJatxoGz4de_IMPoNZJOUAhbHY2j7KD_4fR38oMpf0qFjUBd15_QNaVKiHbjM5WE0emhPAvcNcagGm1rnILLJptARAtBWPhtQ
• https://circleci.com/blog/announcing-our-next-generation-convenience-images-smaller-faster-more-deterministic/

Checklist

• [x] CHANGELOG.md updated
• [x] Rebased/mergeable
• [x] yarn test completes successfully
• [x] Commit messages are in semantic format
• [x] Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #14 (4983168) into master (e649969) will decrease coverage by 2.24%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #14      +/-   ##
==========================================
- Coverage   84.12%   81.87%   -2.25%     
==========================================
  Files           2        2              
  Lines         252      298      +46     
  Branches       32       56      +24     
==========================================
+ Hits          212      244      +32     
- Misses         35       49      +14     
  Partials        5        5              

Impacted Files	Coverage Δ
src/Connector.js	38.63% <0.00%> (-3.40%)	:arrow_down:
src/InfluxDBClient.js	100.00% <0.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update e649969...4983168. Read the comment docs.