[release-v0.37.x] bump github.com/sigstore/cosign/v2 from 2.6.2 to 2.6.3 - #2975

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830, actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683, github/codeql-action/analyze@820e3160e279568db735cee8ed8f8e77a6da7818, github/codeql-action/init@820e3160e279568db735cee8ed8f8e77a6da7818. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/