logger: convert js to ts

The error that is mentioned below can be fixed by enabling
esModuleInterop:

```
logger.ts:1:8 - error TS1259: Module '"/bot/node_modules/winston/index"' can only be default-imported using the 'esModuleInterop' flag

1 import winston from 'winston';
         ~~~~~~~

  node_modules/winston/index.d.ts:213:1
    213 export = winston;
        ~~~~~~~~~~~~~~~~~
    This module is declared with 'export =', and can only be used with a default import when using the 'esModuleInterop' flag.
```

db_connect.js

@@ -1,5 +1,5 @@
 const mongoose = require('mongoose');
-const logger = require('./logger');
+const logger = require('./logger').default;
 
 // connect to database
 const credentials = process.env.DB_USER

logger.js → logger.ts

@@ -1,4 +1,4 @@
-const winston = require('winston');
+import winston from 'winston';
 
 const level = process.env.LOG_LEVEL || 'notice';
 
@@ -9,9 +9,8 @@ const logger = winston.createLogger({
     }),
     winston.format.colorize(),
     winston.format.printf(info => {
-      return `[${info.timestamp}] ${info.level}: ${info.message} ${
-        info.stack ? info.stack : ''
-      }`;
+      return `[${info.timestamp}] ${info.level}: ${info.message} ${info.stack ? info.stack : ''
+        }`;
     })
   ),
   levels: winston.config.syslog.levels,
@@ -24,4 +23,5 @@ const logger = winston.createLogger({
   exitOnError: false,
 });
 
-module.exports = logger;
+
+export default logger;

tsconfig.json

@@ -1,5 +1,6 @@
 {
   "compilerOptions": {
     "strict": true,
+    "esModuleInterop": true
   }
 }