[build] Fix vulnerability in serialize-javascript <=7.0.2

```
npm audit report

serialize-javascript  <=7.0.2
Severity: high
Serialize JavaScript is Vulnerable to RCE via RegExp.flags and Date.prototype.toISOString() - GHSA-5c6j-r48x-rmvq
fix available via `npm audit fix --force`
Will install mocha@7.2.0, which is a breaking change
node_modules/serialize-javascript
  mocha  8.0.0 - 12.0.0-beta-2
  Depends on vulnerable versions of serialize-javascript
  node_modules/mocha
  terser-webpack-plugin  <=5.3.16
  Depends on vulnerable versions of serialize-javascript
  node_modules/terser-webpack-plugin

3 high severity vulnerabilities
```

Fixes: https://github.com/redhat-developer/vscode-openshift-tools/security/dependabot/122

Signed-off-by: Victor Rubezhny <vrubezhny@redhat.com>

Author: vrubezhny