Update Go version in .env and Dockerfile.distroless

- Update GO_VERSION in .env: 1.25.7 → 1.25.8
- Update Dockerfile.distroless FROM golang:1.25.7 → 1.25.8

Addresses review comment to update all Go version occurrences.

Co-Authored-By: Claude Opus 4.6 <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=1.25.7
+GO_VERSION=1.25.8
 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.distroless

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.25.7 AS builder
+FROM golang:1.25.8 AS builder
 
 WORKDIR /workspace
 # Copy the Go Modules manifests