Fix declarations

Author: thdxr

tsconfig-cjs.json

@@ -1,6 +1,7 @@
 {
   "extends": "./tsconfig.json",
   "compilerOptions": {
+    "declaration": true,
     "module": "CommonJS",
     "outDir": "dist/cjs"
   }

tsconfig-esm.json

@@ -1,6 +1,7 @@
 {
   "extends": "./tsconfig.json",
   "compilerOptions": {
+    "declaration": true,
     "module": "ESNext",
     "outDir": "dist/esm"
   }