add formatters to pino's LoggerOptions (#43847)

A new option that deprecates other ones, please see https://github.com/pinojs/pino/blob/master/docs/api.md\#formatters-object for more details.

Signed-off-by: Naseem <naseem@transit.app>

types/pino/index.d.ts

@@ -1,4 +1,4 @@
-// Type definitions for pino 5.17
+// Type definitions for pino 6.0
 // Project: https://github.com/pinojs/pino.git, http://getpino.io
 // Definitions by: Peter Snider <https://github.com/psnider>
 //                 BendingBender <https://github.com/BendingBender>
@@ -444,6 +444,35 @@ declare namespace P {
          * key-value object added as child logger to each log line. If set to null the base child logger is not added
          */
         base?: { [key: string]: any } | null;
+
+        /**
+         * An object containing functions for formatting the shape of the log lines.
+         * These functions should return a JSONifiable object and should never throw.
+         * These functions allow for full customization of the resulting log lines.
+         * For example, they can be used to change the level key name or to enrich the default metadata.
+         */
+        formatters?: {
+          /**
+           * Changes the shape of the log level.
+           * The default shape is { level: number }.
+           * The function takes two arguments, the label of the level (e.g. 'info') and the numeric value (e.g. 30).
+           */
+          level?: (level: string, number: number) => object;
+          /**
+           * Changes the shape of the bindings.
+           * The default shape is { pid, hostname }.
+           * The function takes a single argument, the bindings object.
+           * It will be called every time a child logger is created.
+           */
+          bindings?: (bindings: Bindings) => object;
+          /**
+           * Changes the shape of the log object.
+           * This function will be called every time one of the log methods (such as .info) is called.
+           * All arguments passed to the log method, except the message, will be pass to this function.
+           * By default it does not change the shape of the log object.
+           */
+          log?: (object: object) => object;
+        };
     }
 
     interface PrettyOptions {