Add missing migration for PDFFile

aleksis/core/migrations/0014_alter_pdffile_file.py

+# Generated by Django 3.2 on 2021-04-17 18:47
+
+import aleksis.core.models
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0013_pdf_file'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='pdffile',
+            name='file',
+            field=models.FileField(blank=True, null=True, upload_to=aleksis.core.models.PDFFile._get_upload_path, verbose_name='Generated PDF file'),
+        ),
+    ]