Can't use proxy

[misterunknown]

Hi,

unfortunately this package does not recognize proxy settings. I fixed that by using @actions/http-client:

diff --git a/src/MSTeams.js b/src/MSTeams.js
index a4a4bf0..9ef2f1f 100644
--- a/src/MSTeams.js
+++ b/src/MSTeams.js
@@ -1,6 +1,7 @@
 const {IncomingWebhook} = require('ms-teams-webhook');
 const {context: github} = require('@actions/github');
 const core = require('@actions/core');
+const http = require('@actions/http-client');
 
 const placeholder = '';
 const {
@@ -277,8 +278,8 @@ class MSTeams {
    * @returns {Promise} result
    */
   async notify(url, payload) {
-    const client = new IncomingWebhook(url);
-    const response = await client.send(payload);
+    const client = new http.HttpClient();
+    const response = await client.postJson(url, payload);
 
     if (!response.text) {
       throw new Error('Failed to send notification to Microsoft Teams.\n' + 'Response:\n' + JSON.stringify(response, null, 2));

I'd like to make a pull request, but unfortunately I'm an absolute noob in regards to NodeJS/npm and my pre-commit hook keeps failing. Maybe you can implement this yourself, since @actions/http-client works with proxy settings.

Cheers,
Marco

[BenjaminSchweizer]

proxy support would be awesome