Configure multi-ecosystem grouping for .NET SDK Dependabot updates

[Copilot]

PRs #831 and #832 are updating the same .NET SDK version but split across dotnet-sdk and docker ecosystems. This creates redundant PRs for coordinated changes.

Changes

Added multi-ecosystem group to consolidate .NET SDK updates:

multi-ecosystem-groups:
  dotnet-sdk-updates:
    schedule:
      interval: "weekly"

updates:
  - package-ecosystem: "docker"
    directory: "/EssentialCSharp.Web/"
    patterns: ["*"]
    multi-ecosystem-group: "dotnet-sdk-updates"
    
  - package-ecosystem: "dotnet-sdk"
    directory: "/"
    patterns: ["*"]
    multi-ecosystem-group: "dotnet-sdk-updates"

The patterns key is required when using multi-ecosystem-group. Both ecosystems now reference the same group name to create a single weekly PR containing updates to both Dockerfile and global.json.

Original prompt

#832

#831

Opened two separate PRs for dependabot but these should be grouped together. How do we configure dependabot to group these changes together in the same pr.

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[Copilot]

Pull request overview

This PR configures multi-ecosystem grouping to consolidate .NET SDK Dependabot updates from the docker and dotnet-sdk ecosystems into a single weekly PR, addressing the issue where updates to the same SDK version were being split across separate PRs (#831 and #832).

Changes:

• Added multi-ecosystem-groups configuration with a dotnet-sdk-updates group
• Configured both docker and dotnet-sdk package ecosystems to reference the new multi-ecosystem group
• Added patterns fields to both ecosystem configurations

[Copilot]

The multi-ecosystem-groups section is incorrectly indented. In YAML, top-level keys should start at column 0, but this section appears to be indented at the same level as the registries content. This will cause a YAML parsing error. The multi-ecosystem-groups key should be at the root level, aligned with version, registries, and updates.

[Copilot]

According to Dependabot's multi-ecosystem grouping documentation, the patterns field is used to match dependency names within a single ecosystem's groups configuration. However, when using multi-ecosystem-group, this field is not valid at the ecosystem level. The patterns configuration should instead be part of the multi-ecosystem group definition itself if needed to filter which dependencies are grouped. Remove the patterns fields from the individual ecosystem configurations.

[Copilot]

According to Dependabot's multi-ecosystem grouping documentation, the patterns field is used to match dependency names within a single ecosystem's groups configuration. However, when using multi-ecosystem-group, this field is not valid at the ecosystem level. The patterns configuration should instead be part of the multi-ecosystem group definition itself if needed to filter which dependencies are grouped. Remove the patterns fields from the individual ecosystem configurations.