fix: Migrate LanguagesTaxnomy._taxonomy_class to reflect refactoring (#489)

Fixes an error along the lines of:
    Unable to import taxonomy_class for -1:
    openedx_tagging.core.tagging.models.system_defined.LanguageTaxonomy

This was missed in: #470
We had updated migration 0012 to initialize LanguagesTaxonomy with the
post-refactoring _taxonomy_class, but didn't add a new data migration
to fix the classpath. Migration 0019 now fixes that.
This commit also reverts our change to 0012 for the sake of historical
continuity (but it doesn't really matter either way since 0019 will overwrite
the _taxonomy_class).

Bumps patch version -> 0.34.2

Co-authored-by: Claude Code <noreply@anthropic.com>

Author: kdmccormick

src/openedx_core/__init__.py

@@ -6,4 +6,4 @@
 """
 
 # The version for the entire repository
-__version__ = "0.34.1"
+__version__ = "0.34.2"

src/openedx_tagging/migrations/0012_language_taxonomy.py

@@ -18,7 +18,7 @@ def create_language_taxonomy(apps, schema_editor):
         "allow_multiple": False,
         "allow_free_text": False,
         "visible_to_authors": True,
-        "_taxonomy_class": "openedx_tagging.models.system_defined.LanguageTaxonomy",
+        "_taxonomy_class": "openedx_tagging.core.tagging.models.system_defined.LanguageTaxonomy",
     })
 
     # But delete any unused tags created by the old fixture:

src/openedx_tagging/migrations/0019_language_taxonomy_class.py

@@ -0,0 +1,33 @@
+"""
+Data migration to update the _taxonomy_class on the Languages system taxonomy
+to reflect the new module path after the package rename.
+
+Old: openedx_tagging.core.tagging.models.system_defined.LanguageTaxonomy
+New: openedx_tagging.models.system_defined.LanguageTaxonomy
+"""
+
+from django.db import migrations
+
+OLD_CLASS = "openedx_tagging.core.tagging.models.system_defined.LanguageTaxonomy"
+NEW_CLASS = "openedx_tagging.models.system_defined.LanguageTaxonomy"
+
+
+def update_language_taxonomy_class(apps, schema_editor):
+    Taxonomy = apps.get_model("oel_tagging", "Taxonomy")
+    Taxonomy.objects.filter(_taxonomy_class=OLD_CLASS).update(_taxonomy_class=NEW_CLASS)
+
+
+def revert_language_taxonomy_class(apps, schema_editor):
+    Taxonomy = apps.get_model("oel_tagging", "Taxonomy")
+    Taxonomy.objects.filter(_taxonomy_class=NEW_CLASS).update(_taxonomy_class=OLD_CLASS)
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("oel_tagging", "0018_objecttag_is_copied"),
+    ]
+
+    operations = [
+        migrations.RunPython(update_language_taxonomy_class, revert_language_taxonomy_class),
+    ]