style: format code with Autopep8, Black, ClangFormat, dotnet-format, …

…Go fmt, Gofumpt, Google Java Format, isort, Ktlint, PHP CS Fixer, Prettier, RuboCop, Ruff Formatter, Rustfmt, Scalafmt, StandardJS, StandardRB, swift-format and Yapf

This commit fixes the style issues introduced in 6ec06f1 according to the output
from Autopep8, Black, ClangFormat, dotnet-format, Go fmt, Gofumpt, Google Java
Format, isort, Ktlint, PHP CS Fixer, Prettier, RuboCop, Ruff Formatter, Rustfmt,
Scalafmt, StandardJS, StandardRB, swift-format and Yapf.

Details: None

src/models/transfer.js

@@ -1,12 +1,16 @@
-const mongoose = require("mongoose");
+const mongoose = require('mongoose')
 
 const transferSchema = new mongoose.Schema({
-  sender_id: { type: mongoose.Schema.Types.ObjectId, ref: "User", required: true },
+  sender_id: {
+    type: mongoose.Schema.Types.ObjectId,
+    ref: 'User',
+    required: true
+  },
   receiver_account_id: { type: String, required: true },
   amount: { type: Number, required: true },
-  transaction_hash: { type: String },
-});
+  transaction_hash: { type: String }
+})
 
-const Transfer = mongoose.model("Transfer", transferSchema);
+const Transfer = mongoose.model('Transfer', transferSchema)
 
-module.exports = Transfer;
+module.exports = Transfer