fix(pg): make the tests pass again (DefinitelyTyped#72923)

Author: aqeelat

types/pg/lib/type-overrides.d.ts

@@ -63,7 +63,8 @@ declare enum builtins {
     REGROLE = 4096,
 }
 type TypeId = builtins;
-type TypeParser<I extends (string | Buffer), T> = (value: I) => T;
+type TypeParser<TOid = number, TReturn = any> = (oid: TOid) => TReturn;
+type TypeFormat = 'text' | 'binary';
 
 export = TypeOverrides;
 declare class TypeOverrides implements CustomTypesConfig {
@@ -72,6 +73,5 @@ declare class TypeOverrides implements CustomTypesConfig {
     setTypeParser<T>(oid: number | TypeId, format: "text", parseFn: TypeParser<string, T>): void;
     setTypeParser<T>(oid: number | TypeId, format: "binary", parseFn: TypeParser<Buffer, T>): void;
 
-    getTypeParser<T>(oid: number | TypeId, format?: "text"): TypeParser<string, T | string>;
-    getTypeParser<T>(oid: number | TypeId, format: "binary"): TypeParser<Buffer, T | string>;
+    getTypeParser<T>(oid: number | TypeId, format?: TypeFormat): TypeParser;
 }