ci(deploy): migrate from macos-13 to macos-15-intel

The macos-13 (x86_64) runner image is deprecated. This patch migrates to
macos-15-intel, the last supported Intel-based macOS image for GitHub-
hosted runners.

See:
actions/runner-images#13046
https://github.blog/changelog/2025-09-19-github-actions-macos-13-runner-image-is-closing-down/

Author: tueda

.github/workflows/deploy.yml

@@ -62,8 +62,8 @@ jobs:
           # platforms available.
           - {os: ubuntu-24.04-arm, shell: bash, bin: form}
           - {os: ubuntu-24.04-arm, shell: bash, bin: tform}
-          - {os: macos-13, shell: bash, bin: form}
-          - {os: macos-13, shell: bash, bin: tform}
+          - {os: macos-15-intel, shell: bash, bin: form}
+          - {os: macos-15-intel, shell: bash, bin: tform}
           # The macos-14 runner image is based on the arm64 architecture.
           - {os: macos-14, shell: bash, bin: form}
           - {os: macos-14, shell: bash, bin: tform}
@@ -290,7 +290,7 @@ jobs:
           }
           make_tar_gz x86_64-linux '*-ubuntu-24.04/*form'
           make_tar_gz arm64-linux '*-ubuntu-24.04-arm/*form'
-          make_tar_gz x86_64-osx '*-macos-13/*form'
+          make_tar_gz x86_64-osx '*-macos-15-intel/*form'
           make_tar_gz arm64-osx '*-macos-14/*form'
           make_zip x86_64-windows '*-windows-2022/*form.exe'