Review tests of external-package JSON-Schema generation

[tcompa]

We should review #763 (ref #757).

The current GHA is somewhat useful, but it does not fulfill its stated goal.

Current behavior: re-run manifest creation with the fractal-tasks-core version specified within the package
Expected behavior: run manifest creation with the fractal-tasks-core version from the current git branch (e.g. from a PR)

[tcompa]

We are fixing this as part of #793, with a workaround (see full diff below)

1. Install the external package
2. Get the current version of fractal-tasks-core (from git), and run python -m pip install -e ./fractal-tasks-core

We cannot have a perfectly clean workflow here, because an external package should depend on some specific released versions of fractal-tasks-core, and never on a development git branch.

This strategy works, overall, but it can obviously introduce false positive where the errors are due to different-version features rather than to manifest issues.

---

diff --git a/.github/workflows/manifest_external_packages.yml b/.github/workflows/manifest_external_packages.yml
index e4a471d7..d3b26c56 100644
--- a/.github/workflows/manifest_external_packages.yml
+++ b/.github/workflows/manifest_external_packages.yml
@@ -23,36 +23,46 @@ jobs:
 
         package: [skip]
         github_repo: [skip]
+        github_branch: [skip]
         manifest_path: [skip]
         cmd_install: [skip]
         cmd_create_manifest: [skip]
+        custom_dependencies: [skip]
 
         include:
 
           - package: scMultipleX
             github_repo: fmi-basel/gliberal-scMultipleX
+            github_branch: main
             manifest_path: src/scmultiplex/__FRACTAL_MANIFEST__.json
             cmd_install: 'python -m pip install -e .[fractal-tasks]'
             cmd_create_manifest: 'python src/scmultiplex/dev/create_manifest.py'
+            custom_dependencies: 'image_registration'
 
           - package: fractal-helper-tasks
             github_repo: jluethi/fractal-helper-tasks
+            github_branch: main
             manifest_path: src/fractal_helper_tasks/__FRACTAL_MANIFEST__.json
             cmd_install: 'python -m pip install -e .'
             cmd_create_manifest: 'python src/fractal_helper_tasks/dev/create_manifest.py'
+            custom_dependencies: ''
 
           - package: APx_fractal_task_collection
             github_repo: Apricot-Therapeutics/APx_fractal_task_collection
+            github_branch: pydantic_v2
             manifest_path: src/apx_fractal_task_collection/__FRACTAL_MANIFEST__.json
             cmd_install: 'python -m pip install -e .'
             cmd_create_manifest: 'python src/apx_fractal_task_collection/dev/update_manifest.py'
+            custom_dependencies: ''
 
         exclude:
           - package: skip
             github_repo: skip
+            github_branch: skip
             manifest_path: skip
             cmd_install: skip
             cmd_create_manifest: skip
+            custom_dependencies: skip
 
     steps:
 
@@ -63,6 +73,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: ${{ matrix.github_repo }}
+          ref: ${{ matrix.github_branch }}
 
       - uses: actions/setup-python@v5
         with:
@@ -75,11 +86,29 @@ jobs:
       - name: Install package
         run:  ${{ matrix.cmd_install }}
 
+      - name: Get current branch of `fractal-tasks-core`
+        uses: actions/checkout@v4
+        with:
+          path: fractal-tasks-core
+
+      - name: Install current fractal-tasks-core (this may fail)
+        run: python -m pip install -e ./fractal-tasks-core
+
+      - name: Install custom additional dependencies (see issue 803)
+        if: ${{ matrix.custom_dependencies != '' }}
+        run: python -m pip install ${{ matrix.custom_dependencies }}
+
       - name: Create manifest
         run: ${{ matrix.cmd_create_manifest }}
 
+      - name: Setup friendly diff style
+        run: echo "*.json diff=json" >> .gitattributes && git config diff.json.textconv "jq --sort-keys '.' \$1"
+
       - name: Run git diff for manifest
         run: git diff ${{ matrix.manifest_path }}
 
+      - name: Clean up before checking repo status
+        run: rm -rf fractal-tasks-core .gitattributes
+
       - name: Check repo status
         run: if [[ -z $(git status -s) ]]; then echo "Clean status"; else echo "Dirty status"; git status; exit 1; fi