build(deps): bump library/golang from 1.25.5-alpine to 1.26rc2-alpine

Bumps library/golang from 1.25.5-alpine to 1.26rc2-alpine.

---
updated-dependencies:
- dependency-name: library/golang
  dependency-version: 1.26rc2-alpine
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Dockerfile.test

@@ -9,7 +9,7 @@ RUN [ "go", "test", "-v", "./internal/cli/...", "-run", "TestGenerate_InstallDeb
 
 # This line also determines the golang version used for GitHub Actions CI
 # Use the qualified image name, so Dependabot treats this separate from "golang" above.
-FROM docker.io/library/golang:1.25.5-alpine AS apk
+FROM docker.io/library/golang:1.26rc2-alpine AS apk
 ENV CGO_ENABLED=0
 WORKDIR /app
 COPY go.mod .