Add 2625. Flatten Deeply Nested Array solution, add .hintrc, and remove verify_sri.py

Author: myoshi2891

.hintrc

@@ -0,0 +1,8 @@
+{
+  "extends": [
+    "development"
+  ],
+  "hints": {
+    "no-inline-styles": "off"
+  }
+}