Update Go version to 1.26.2 in Dockerfiles and .env

Update Go version references in build configuration files to match
the go.mod update for VULN-71182 compliance.

Files updated:
- Dockerfile: golang:1.25.8 -> golang:1.26.2
- Dockerfile.distroless: golang:1.25.8 -> golang:1.26.2
- .env: GO_VERSION=1.25.8 -> GO_VERSION=1.26.2

GitHub Actions workflows automatically use GO_VERSION from .env,
so no workflow file changes are needed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: gabrielm-splunk

.env

@@ -1,6 +1,6 @@
 OPERATOR_SDK_VERSION=v1.42.0
 REVIEWERS=vivekr-splunk,rlieberman-splunk,patrykw-splunk,Igor-splunk,kasiakoziol,kubabuczak,gabrielm-splunk,minjieqiu,qingw-splunk
-GO_VERSION=1.25.8
+GO_VERSION=1.26.2
 AWSCLI_URL=https://awscli.amazonaws.com/awscli-exe-linux-x86_64-2.8.6.zip
 KUBECTL_VERSION=v1.29.1
 AZ_CLI_VERSION=2.79.0

Dockerfile

@@ -5,7 +5,7 @@ ARG BASE_IMAGE=registry.access.redhat.com/ubi8/ubi-minimal
 ARG BASE_IMAGE_VERSION=8.10-1775152441
 
 # Build the manager binary
-FROM golang:1.25.8 AS builder
+FROM golang:1.26.2 AS builder
 
 WORKDIR /workspace
 

Dockerfile.distroless

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.25.8 AS builder
+FROM golang:1.26.2 AS builder
 
 WORKDIR /workspace
 # Copy the Go Modules manifests