ci: remove arm/v7 platform from Docker build

The uv builder image (ghcr.io/astral-sh/uv:0.5-python3.12-alpine) only
supports amd64 and arm64, not arm/v7.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people

.github/workflows/build.yml

@@ -238,7 +238,7 @@ jobs:
         with:
           context: .
           builder: ${{ steps.buildx.output.name }}
-          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          platforms: linux/amd64,linux/arm64
           push: True
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
@@ -251,7 +251,7 @@ jobs:
         with:
           context: .
           builder: ${{ steps.buildx.output.name }}
-          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          platforms: linux/amd64,linux/arm64
           push: ${{ github.event_name == 'push' }}
           tags: ${{ steps.meta-dev.outputs.tags }}
           labels: ${{ steps.meta-dev.outputs.labels }}
@@ -264,7 +264,7 @@ jobs:
         with:
           context: .
           builder: ${{ steps.buildx.output.name }}
-          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          platforms: linux/amd64,linux/arm64
           push: false
           tags: estrellaxd/auto_bangumi:test
           cache-from: type=gha, scope=${{ github.workflow }}