Upgrade apollo-server-express to 2.21.0

[davimacedo]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Related issue: FILL_THIS_OUT

Approach

TODOs before merging

• Add test cases
• Add entry to changelog
• Add changes to documentation (guides, repository pages, in-code descriptions)
• Add security check
• Add new Parse Error codes to Parse JS SDK
• ...

[codecov]

Codecov Report

Merging #7266 (157f06f) into master (9563793) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7266      +/-   ##
==========================================
- Coverage   94.01%   94.00%   -0.02%     
==========================================
  Files         179      179              
  Lines       13140    13140              
==========================================
- Hits        12354    12352       -2     
- Misses        786      788       +2     

Impacted Files	Coverage Δ
src/ParseServerRESTController.js	97.01% <0.00%> (-1.50%)	⬇️
src/Adapters/Files/GridFSBucketAdapter.js	79.50% <0.00%> (-0.82%)	⬇️

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[parseplatformorg]

🎉 This change has been released in version 5.0.0-beta.1

[parseplatformorg]

🎉 This change has been released in version 5.0.0