feat(db): add an index for SSHPubKeys.PubKey (#2)

Speeds up SSHPubKeys.PubKey searches in a larger database.

Fixed form of the original commit which was reverted,
1a7f6e1fa9

Signed-off-by: Kevin Morris <kevr@0cost.org>

test/test_migration.py

@@ -0,0 +1,23 @@
+import pytest
+
+from sqlalchemy import inspect
+
+from aurweb.db import get_engine
+from aurweb.models.ssh_pub_key import SSHPubKey
+
+
+@pytest.fixture(autouse=True)
+def setup(db_test):
+    return
+
+
+def test_sshpubkeys_pubkey_index():
+    insp = inspect(get_engine())
+    indexes = insp.get_indexes(SSHPubKey.__tablename__)
+
+    found_pk = False
+    for idx in indexes:
+        if idx.get("name") == "SSHPubKeysPubKey":
+            assert idx.get("column_names") == ["PubKey"]
+            found_pk = True
+    assert found_pk