Update Kubernetes packages to v1.20.4

[stefanprodan]

Changes:

• Update Kubernetes packages to v1.20.4
• Update Alpine to v3.13 in Flagger Dockerfile
• Merge FOSSA and CodeQL workflows in CI

[codecov-io]

Codecov Report

Merging #857 (e9c3518) into main (16867db) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #857   +/-   ##
=======================================
  Coverage   56.72%   56.72%           
=======================================
  Files          67       67           
  Lines        5430     5430           
=======================================
  Hits         3080     3080           
  Misses       1890     1890           
  Partials      460      460           

Impacted Files	Coverage Δ
pkg/canary/config_tracker.go	83.25% <0.00%> (ø)

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