chore(deps): update node.js to v21

[renovate]

This PR contains the following updates:

Package	Update	Change
node	major	20.9 -> 21.1

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[USA-RedDragon]

Blocked by dart-lang/sdk#53784

[codecov]

Codecov Report

Merging #511 (c373dfe) into main (6e0af0f) will increase coverage by 14.81%.
Report is 586 commits behind head on main.
The diff coverage is 14.56%.

@@            Coverage Diff             @@
##            main     #511       +/-   ##
==========================================
+ Coverage   8.86%   23.67%   +14.81%     
==========================================
  Files         66       53       -13     
  Lines       9919     7320     -2599     
  Branches      23        0       -23     
==========================================
+ Hits         879     1733      +854     
+ Misses      8913     5587     -3326     
+ Partials     127        0      -127     

Flag	Coverage Δ
backend	23.67% <14.56%> (+9.05%)	⬆️
frontend-e2e-chrome	?
frontend-e2e-electron	?
frontend-e2e-firefox	?
frontend-unit	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
internal/dmrconst/const.go	66.66% <ø> (ø)
internal/http/api/apimodels/user.go	45.45% <ø> (+27.27%)	⬆️
internal/http/api/controllers/v1/auth/auth.go	56.66% <100.00%> (+56.66%)	⬆️
...nal/http/api/controllers/v1/lastheard/lastheard.go	0.00% <ø> (ø)
internal/http/api/middleware/database.go	100.00% <ø> (ø)
internal/http/api/middleware/paginated_database.go	54.34% <ø> (+10.86%)	⬆️
internal/http/api/middleware/redis.go	100.00% <ø> (ø)
internal/http/api/middleware/tracing.go	0.00% <ø> (ø)
internal/http/api/pagination/pagination.go	100.00% <ø> (+66.66%)	⬆️
internal/http/api/utils/password.go	70.96% <ø> (+36.55%)	⬆️
... and 43 more

... and 23 files with indirect coverage changes

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