build: bugfix typings + bump version

node_modules/ajv/dist/types/json-schema.d.ts:1:92 - error TS1005: '?' expected.

1 declare type StrictNullChecksWrapper<Name extends string, Type> = undefined extends null ? `strictNullChecks must be true in tsconfig to use ${Name}` : Type;

see ajv-validator/ajv#1930
--> using the same typescript version range as angularfire

engine/engine.ts:272:7 - error TS2794: Expected 1 arguments, but got 0. Did you forget to include 'void' in your type argument to 'Promise'?

272       resolve();

src/engine/engine.ts

@@ -269,7 +269,7 @@ async function publishViaGhPages(
         return reject(error);
       }
 
-      resolve();
+      resolve(undefined);
     });
   });
 }