Yarn package install does not use custom.prisma.version

[kyle-swanson]

runPackageInstallCommand doesn't use the param from custom.prisma.version if webpack packager is set to yarn.

The issue seems to be in

runPackageInstallCommand({ packageName, cwd, dev }) {
    let params = '';
    let version = this.getPrismaVerisonParam();
    if (dev) params += '-D ';
    if (version) version = `@${version}`;
    const command =
      this.getPackageManager() === 'npm'
        ? `npm install ${params}${packageName}${version}`
        : `yarn add ${params}${packageName}`; // Missing ${version}
    childProcess.execSync(command, { cwd });
  }

prisma is always installed at the latest version when using Yarn.