Use dataclasses to define activitypub (de)serialization (#177)

* Use dataclasses to define activitypub (de)serialization

fedireads/migrations/0042_auto_20200524_0346.py

@@ -0,0 +1,21 @@
+# Generated by Django 3.0.3 on 2020-05-24 03:46
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fedireads', '0041_user_remote_id'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='status',
+            name='activity_type',
+        ),
+        migrations.RemoveField(
+            model_name='status',
+            name='status_type',
+        ),
+    ]

fedireads/migrations/0045_merge_20200810_2010.py

@@ -0,0 +1,14 @@
+# Generated by Django 3.0.7 on 2020-08-10 20:10
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fedireads', '0044_siteinvite_user'),
+        ('fedireads', '0042_auto_20200524_0346'),
+    ]
+
+    operations = [
+    ]