fix: allow writing statuses on PRs

[lidel]

This aims to restore "Preview on IPFS" badges broken by github's security hardening this year

Ref.

• https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#permissions

[github-actions]

Diff of Changes

Old: /ipns/dist.ipfs.io at /ipfs/QmX2KTMXiUb6tHTMS1JynhyQaL9qoj6uf1SLzHPhzGNnDv
New: /ipfs/QmUjMfTG5DUv3t4PJi73rovMzhqJaRSiGfQwTRtJiAXtx6

diff --new-file -u --recursive a/index.xml b/index.xml
--- a/index.xml 2021-08-06 13:56:11.129570958 +0000
+++ b/index.xml 2021-08-06 13:56:11.085570192 +0000
@@ -6,7 +6,7 @@
 <description>Recent releases on IPFS Distributions</description>
 <generator>Hugo -- gohugo.io</generator>
 <language>en-us</language>
- <lastBuildDate>Wed, 21 Jul 2021 17:22:21 +0000</lastBuildDate>
+ <lastBuildDate>Wed, 21 Jul 2021 00:00:00 GMT</lastBuildDate>
 
 <atom:link href="https://dist.ipfs.io/index.xml" rel="self" type="application/rss&#43;xml" />