Support for newer typescript version

[DeyLak]

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used patch-package to patch react-vega@7.6.0 for the project I'm working on.

I used it with typescript 4.9.4 and got an error

Here is the diff that solved my problem:

diff --git a/node_modules/react-vega/src/utils/getUniqueFieldNames.ts b/node_modules/react-vega/src/utils/getUniqueFieldNames.ts
index cc9c643..74174a1 100644
--- a/node_modules/react-vega/src/utils/getUniqueFieldNames.ts
+++ b/node_modules/react-vega/src/utils/getUniqueFieldNames.ts
@@ -1,4 +1,4 @@
-export default function getUniqueFieldNames<T>(objects: T[]) {
+export default function getUniqueFieldNames<T extends object>(objects: T[]) {
   const fields = new Set<string>();
   objects.forEach(o => {
     Object.keys(o).forEach(field => {

This issue body was partially generated by patch-package.