Update url for collect_env.py (#3271)

Summary:
The `master` branch of PyTorch has been updated to `main` recently. The url of `collect_env.py` in the new issue page should be updated as well.

Pull Request resolved: https://github.com/pytorch/audio/pull/3271

Reviewed By: xiaohui-zhang

Differential Revision: D45087038

Pulled By: nateanl

fbshipit-source-id: 167262ae6ed179baabcf55064fc5f0f0ac3b0be9

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -50,7 +50,7 @@ body:
     description: |
       Please run the following and paste the output below.
       ```sh
-      wget https://raw.githubusercontent.com/pytorch/pytorch/master/torch/utils/collect_env.py
+      wget https://raw.githubusercontent.com/pytorch/pytorch/main/torch/utils/collect_env.py
       # For security purposes, please check the contents of collect_env.py before running it.
       python collect_env.py
       ```