chore: Bump go version to 1.23.6 (#326)

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**Description**

Changes proposed in this pull request:

- Bump used go version to latest v.1.23.6

**Related issue(s)**
<!-- If you refer to a particular issue, provide its number. For
example, `Resolves #123`, `Fixes #43`, or `See also #33`. -->

Dockerfile

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.23.5-alpine as builder
+FROM golang:1.23.6-alpine as builder
 ARG TARGETOS
 ARG TARGETARCH
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/kyma-project/template-operator
 
-go 1.23.5
+go 1.23.6
 
 replace github.com/kyma-project/template-operator/api => ./api