message: Add net core version checker
diff: +import util = require("util");
  +import semver = require("semver");
  export default class NetCoreChecker implements IDependencyChecker {
  + private exec = util.promisify(require("child_process").exec);
  + private NETCORE_REGEX = RegExp("([0-9.]+)");
  + private NETCORE_REQUIREMENT = ">=3.1.x";
  +
  public async hasDependency() {
  - return await new Promise<boolean>(() => true);
  + try {
  + const { stdout } = await this.exec("dotnet --version");
  + const version = stdout.match(this.NETCORE_REGEX)[1];
  + const result = semver.satisfies(version, this.NETCORE_REQUIREMENT);
  + return result;
  + } catch (err) {
  + return false;
  + }
  }
  }
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