Update package.json (#54)

downgraded material ui packages

Author: Abhay-soni-developer

package.json

@@ -35,7 +35,7 @@
     "@backstage/core-plugin-api": "^1.3.0",
     "@backstage/errors": "^1.1.4",
     "@backstage/theme": "^0.2.16",
-    "@material-table/core": "^6.2.1",
+    "@material-table/core": "v3.1.0",
     "@material-ui/core": "^4.12.2",
     "@material-ui/icons": "^4.9.1",
     "@material-ui/lab": "^4.0.0-alpha.57",