babelrc: Bump supported browser versions

Commit fc73c07195 added a check for String.replaceAll(), update to the
browsers which support that. These correspond to our website:
https://github.com/cockpit-project/cockpit-project.github.io/commit/ea70505944

.babelrc.json

@@ -2,11 +2,10 @@
     "presets": [
         ["@babel/env", {
             "targets": {
-                "chrome": "57",
+                "chrome": "85",
-                "firefox": "52",
+                "firefox": "77",
-                "safari": "10.3",
+                "safari": "13.4",
-                "edge": "16",
+                "edge": "85"
-                "opera": "44"
             }
         }],
         "@babel/preset-react"