fix: complete periodic table (#656)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Added new elements to the periodic table: Rf, Db, Sg, Bh, Hs, Mt, Ds,
Rg, Cn, Nh, Fl, Mc, Lv, Ts, Og.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

dpdata/periodic_table.py

@@ -108,6 +108,21 @@
     "Md",
     "No",
     "Lr",
+    "Rf",
+    "Db",
+    "Sg",
+    "Bh",
+    "Hs",
+    "Mt",
+    "Ds",
+    "Rg",
+    "Cn",
+    "Nh",
+    "Fl",
+    "Mc",
+    "Lv",
+    "Ts",
+    "Og",
 ]