Add .node-version

Node version 16 or --openssl-legacy-provider required to avoid error:

Error: error:0308010C:digital envelope routines::unsupported
    at new Hash (node:internal/crypto/hash:101:19)
    at Object.createHash (node:crypto:145:10)
    at BulkUpdateDecorator.hashFactory (/Users/mwoods/code/vim-language-server/node_modules/webpack/lib/util/createHash.js:144:18)
    at BulkUpdateDecorator.update (/Users/mwoods/code/vim-language-server/node_modules/webpack/lib/util/createHash.js:46:50)
    at RawSource.updateHash (/Users/mwoods/code/vim-language-server/node_modules/webpack-sources/lib/RawSource.js:64:8)
    at NormalModule._initBuildHash (/Users/mwoods/code/vim-language-server/node_modules/webpack/lib/NormalModule.js:838:17)
    at handleParseResult (/Users/mwoods/code/vim-language-server/node_modules/webpack/lib/NormalModule.js:903:10)
    at /Users/mwoods/code/vim-language-server/node_modules/webpack/lib/NormalModule.js:994:4
    at processResult (/Users/mwoods/code/vim-language-server/node_modules/webpack/lib/NormalModule.js:717:11)
    at /Users/mwoods/code/vim-language-server/node_modules/webpack/lib/NormalModule.js:777:5 {
  opensslErrorStack: [
    'error:03000086:digital envelope routines::initialization error',
    'error:0308010C:digital envelope routines::unsupported'
  ],
  library: 'digital envelope routines',
  reason: 'unsupported',
  code: 'ERR_OSSL_EVP_UNSUPPORTED'
}

Proper fix is to upgrade dependencies, but one step at a time

Author: mmrwoods

.node-version

@@ -0,0 +1 @@
+16.20.2