Latest apollo (2.32.10) breaks/drops node 15 support

Upgrading apollo from 2.23.5 to 2.32.10 is giving compatibility errors when using node 15. This might be intentional, but if it was mentioned in any of the changelogs I missed it.

```
$ npm ls @apollo/federation
ui@0.1.0
└─┬ apollo@2.32.5
└─┬ apollo-language-server@1.25.2
└── @apollo/federation@0.20.7

$ grep '"node":' node_modules/apollo/package.json
"node": ">=8",
$ grep '"node":' node_modules/apollo-language-server/package.json
"node": ">=8",
$ grep '"node":' node_modules/@apollo/federation/package.json
"node": ">=8"
```

```
$ npm ls @apollo/federation
ui@0.1.0
└─┬ apollo@2.32.10
└─┬ apollo-language-server@1.25.7
└── @apollo/federation@0.23.1

$ grep '"node":' node_modules/apollo/package.json
"node": ">=8",
$ grep '"node":' node_modules/apollo-language-server/package.json
"node": ">=8",
$ grep '"node":' node_modules/@apollo/federation/package.json
"node": ">=12.13.0 <15.0"
```

Start by reproducing the upgrade from apollo 2.23.5 to 2.32.10 under Node 15 and compare the referenced package.json engine entries for apollo, apollo-language-server, and @apollo/federation. Check the relevant changelog entries; done means the Node 15 support status and the source of the compatibility change are established.

Written by the indexing model from the issue text.