Add template file for tutorial pages

[ehogan]

Description

• Closes Add template file for tutorial pages #4452
• Link to documentation: https://esmvaltool--4456.org.readthedocs.build/en/4456/tutorials/template.html

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[ehogan]

I tried following the instructions provided by "🛠 Any changed dependencies have been added or removed correctly" but I got:

 WARN the lock file is up-to-date but uses an older format (v6), re-solving all environments using locked content to upgrade to v7
Error:   × failed to solve requirements of environment 'test-py312' for platform 'osx-arm64'
  ├─▶   × a coalesced request failed
  │   
  ╰─▶ other error

@bouweandela would it be possible for you to help with this, please? 🤞