fix(devtools): circular ref on observer stringify

[DamianOsipiuk]

Fixes #131

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://vercel.com/damianosipiuk/vue-query/BKuumeWeB5UxYogwfxg5dVonDzpm
✅ Preview: https://vue-query-git-fix-circular-ref-on-strigify-damianosipiuk.vercel.app

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 888716d:

Sandbox	Source
DamianOsipiuk/vue-query: basic	Configuration
DamianOsipiuk/vue-query: 2.x-basic	Configuration
DamianOsipiuk/vue-query: nuxt-simple	Configuration
gracious-forest-gb0pub	Issue #131

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #134 (888716d) into main (66fd6aa) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #134   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           14        14           
  Lines          266       266           
  Branches        51        51           
=========================================
  Hits           266       266           

---

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 66fd6aa...888716d. Read the comment docs.

[github-actions]

🎉 This PR is included in version 1.19.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀