Error with body_path when no PR is created

[laeubi]

Example is https://github.com/eclipse-equinox/p2/actions/runs/12877581441/job/35902256031

Run peter-evans/create-pull-request@c5a7806660adbe173f04e3e038b0ccdcd758773c
  with:
    commit-message: Update version ranges of dependencies for bundles/org.eclipse.equinox.frameworkadmin.equinox
    branch: dependency-check/bundles/org.eclipse.equinox.frameworkadmin.equinox
    title: Update version ranges of dependencies for bundles/org.eclipse.equinox.frameworkadmin.equinox
    body-path: bundles/org.eclipse.equinox.frameworkadmin.equinox/target/versionProblems.md
    delete-branch: true
    draft: false
    token: ***
    committer: Eclipse Equinox Bot <equinox-bot@eclipse.org>
    author: Eclipse Equinox Bot <equinox-bot@eclipse.org>
    add-paths: **/*.MF
  
    signoff: false
    body: Automated changes by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action
  env:
    JAVA_HOME: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/17.0.13-11/x64
    JAVA_HOME_17_X64: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/17.0.13-11/x64
Error: File 'bundles/org.eclipse.equinox.frameworkadmin.equinox/target/versionProblems.md' does not exist.

while it is correct that the file is not present, this is because no changes where made and thus also the PR would not be created.

It would be good if reading the file would be delayed until the point where the PR is actually created, so if no changes are detected the file is not needed.

Current workaround is to always create a dummy file (and of course exclude it from the PR creation)