fix missing template tag (#9000)

src/backend/InvenTree/InvenTree/templatetags/inventree_extras.py

@@ -117,6 +117,12 @@ def inventree_commit_hash(*args, **kwargs):
     return version.inventreeCommitHash()
 
 
+@register.simple_tag()
+def inventree_installer(*args, **kwargs):
+    """Return InvenTree package installer string."""
+    return version.inventreeInstaller()
+
+
 @register.simple_tag()
 def inventree_commit_date(*args, **kwargs):
     """Return InvenTree git commit date string."""