chore: add mongodb 4 as possible peer dependency (#37)

Author: lukashass

package.json

@@ -37,7 +37,7 @@
     "@types/node": "15.12.4",
     "eslint": "7.29.0",
     "jest": "26.6.3",
-    "mongodb": "3.6.10",
+    "mongodb": "4.2.2",
     "prettier": "2.3.1",
     "rollup": "2.60.2",
     "rollup-plugin-dts": "4.0.1",
@@ -49,7 +49,7 @@
     "typescript": "4.5.2"
   },
   "peerDependencies": {
-    "mongodb": "^3.6.0"
+    "mongodb": "^3.6.0 || ^4.0.0"
   },
   "peerDependenciesMeta": {
     "mongodb": {