Update dependabot.yml

[pellared]

Why

Per #356 (comment)

What

Fixes following issues

Changes proposed in this pull request:

• Remove the nuget for directories that only contain the Directory.Build.props file
• Increase the "open PR limit"
• Do not set label manually (dependabot set it by its own if it is seft unset)
• Add all directories containing *.csproj

Probably we should use the generated PRs only for sake of "tracking". Thanks to it we are notified about new versions. After we create PRs like #436 we can then check if the PRs are automatically closed.

Some of them we can close manually if we do not want to bump the dependency.

A similar approach is used in https://github.com/open-telemetry/opentelemetry-go and https://github.com/open-telemetry/opentelemetry-go-contrib. The only issue is that it generates a lot of spam GitHub notifications...

Testing

Check https://github.com/pellared/opentelemetry-dotnet-instrumentation-dependabot/pulls

Generating dependabot

I executed find . -type f -name '*.csproj' | sed -r 's|/[^/]+$||' | sort | uniq to all directories containing *.csproj.

Then I have written a little Go program to generate the yml file

package main

import (
	"log"
	"os"
	"text/template"
)

func main() {
	const tplt = `
version: 2
updates:

  - package-ecosystem: github-actions
    directory: /
    schedule:
      day: sunday
      interval: weekly

{{range .}} 
  - package-ecosystem: nuget
    directory: {{.}}
    schedule:
      day: sunday
      interval: weekly
    open-pull-requests-limit: 20
{{end}}
`

	folders := []string{
		"/build/nuke",
		"/examples/AspNetCoreMvc",
		"/examples/BindingRedirect",
		"/examples/ConsoleApp",
		"/examples/ConsoleApp.SelfBootstrap",
		"/examples/CoreAppOldReference",
		"/examples/OldReference",
		"/examples/OpenTracingLibrary",
		"/examples/Vendor.Distro",
		"/src/OpenTelemetry.AutoInstrumentation",
		"/src/OpenTelemetry.AutoInstrumentation.AdditionalDeps",
		"/src/OpenTelemetry.AutoInstrumentation.Core",
		"/src/OpenTelemetry.AutoInstrumentation.Loader",
		"/src/OpenTelemetry.AutoInstrumentation.StartupHook",
		"/test/integration-tests/aspnet/IntegrationTests.AspNet",
		"/test/integration-tests/IntegrationTests.GraphQL",
		"/test/integration-tests/IntegrationTests.Helpers",
		"/test/integration-tests/IntegrationTests.MongoDB",
		"/test/integration-tests/IntegrationTests.StartupHook",
		"/test/OpenTelemetry.AutoInstrumentation.Bootstrapping.Tests",
		"/test/OpenTelemetry.AutoInstrumentation.Loader.Tests",
		"/test/OpenTelemetry.AutoInstrumentation.Tests",
		"/test/test-applications/integrations/aspnet/Samples.AspNet",
		"/test/test-applications/integrations/dependency-libs/Samples.ExampleLibrary",
		"/test/test-applications/integrations/dependency-libs/Samples.ExampleLibraryTracer",
		"/test/test-applications/integrations/Samples.GraphQL",
		"/test/test-applications/integrations/Samples.MongoDB",
		"/test/test-applications/integrations/Samples.StartupHook",
		"/test/test-applications/mocks/OpenTelemetry.AutoInstrumentation.Mock",
	}

	t := template.Must(template.New("letter").Parse(tplt))
	if err := t.Execute(os.Stdout, folders); err != nil {
		log.Fatalln("executing template:", err)
	}
}

Probably we could make a Nuke target that does it instead.

[nrcventura]

Thank you for detailing the process that you used!