Upgrade dependencies

[unmarshall]

How to categorize this PR?

/area security
/kind bug

What this PR does / why we need it:
Upgrades the following:

• Go version to 1.20 (CI pipeline changed to use 1.20.3)
• K8S api and api machinery to v1.26.2
• Gomega to v1.27.1
• Zap to v.1.24.0
• Controller-Runtime to v0.14.5
• Code Generator to v0.26.2
• Client-Go to v0.26.2
• Dockerfile to now use golang 1.20.3

Which issue(s) this PR fixes:
Fixes #83

Special notes for your reviewer:

Release note:

Following dependencies are updated:
  Go - 1.20.3 
  client-go - v0.26.2 
  controller-runtime - v0.14.5
  gomega - v1.27.1
  zap - v1.24.0 
  gardener/gardener v1.69.0
  k8s (api and apimachinery) - v0.26.2

[unmarshall]

/invite @himanshu-kun

[himanshu-kun]

Kindly also upgrade the following files:

• https://github.com/gardener/dependency-watchdog/blob/master/Dockerfile

• dependency-watchdog/.ci/pipeline_definitions

  Lines 29 to 34 in 1d08025

  	check:
  	image: 'golang:1.19.4'
  	test-unit:
  	image: 'golang:1.19.4'
  	build:
  	image: 'golang:1.19.4'

Kindly also update the release note to be for others and dependency , and mention to which version each dependency has been updated

[himanshu-kun]

/lgtm

[gardener-prow]

LGTM label has been added.

Git tree hash: 2023779c441a7fc2e69156a6829d4509aea3be21

[gardener-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: himanshu-kun

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• OWNERS [himanshu-kun]

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