Update dockerfile base to node:20-alpine

[jcortejoso]

Update dockerfile to reduce vulnerabilities.

Before:

299 vulnerabilities found in 65 packages
  UNSPECIFIED  2
  LOW          69
  MEDIUM       105
  HIGH         81
  CRITICAL     42

After:

No vulnerable packages detected

[socket-security]

Updated dependencies detected. Learn more about Socket for GitHub ↗︎

Packages	Version	New capabilities	Transitives	Size	Publisher
@angular/material	9.2.0...9.2.4	None	+7/-6	102 MB	google-wombot
@angular/core	9.1.0...9.1.13	None	+1/-0	31.4 MB	google-wombot
@angular/cdk	9.2.0...9.2.4	None	+3/-2	62 MB	google-wombot
@angular/compiler-cli	9.1.0...9.1.13	None	+15/-23	36.2 MB	google-wombot
@angular/platform-browser-dynamic	9.1.0...9.1.13	None	+6/-5	83.7 MB	google-wombot
@angular/service-worker	9.1.0...9.1.13	None	+3/-2	47.7 MB	google-wombot
@angular/language-service	9.1.0...9.1.13	None	+0/-0	3.26 MB	google-wombot
@angular/platform-browser	9.1.0...9.1.13	None	+4/-3	53.9 MB	google-wombot
@angular/router	9.1.0...9.1.13	None	+5/-4	58.7 MB	google-wombot
@angular/animations	9.1.0...9.1.13	None	+2/-1	36.2 MB	google-wombot
@angular/forms	9.1.0...9.1.13	None	+5/-4	58 MB	google-wombot
@angular/common	9.1.0...9.1.13	None	+2/-1	46.9 MB	google-wombot
@angular/compiler	9.1.0...9.1.13	None	+0/-0	29.2 MB	google-wombot
@angular/cli	9.1.0...9.1.15	None	+126/-82	16.7 MB	google-wombot