Add incremental upgrades on the test channel for Tails 3.6.1

wiki/src/upgrade/v1/Tails/3.6/amd64/test/upgrades.yml

+---
+build-target: amd64
+channel: test
+product-name: Tails
+product-version: '3.6'
+upgrades:
+- details-url: https://tails.boum.org/news/version_3.6.1/
+  type: major
+  upgrade-paths:
+  - target-files:
+    - sha256: 826c8fc05a7fb04962c6a45350648fc9273bf98f8b19b2d5a491b440d78ecbf6
+      size: 1225568256
+      url: http://dl.amnesia.boum.org/tails/stable/tails-amd64-3.6.1/tails-amd64-3.6.1.iso
+    type: full
+  - target-files:
+    - sha256: ab91753e2d22fd80ee352f68f331134bb8115566b26eaf46d44e85b36dd1e2d2
+      size: 102461440
+      url: http://dl.amnesia.boum.org/tails/stable/iuk/Tails_amd64_3.6_to_3.6.1.iuk
+    type: incremental
+  version: 3.6.1

wiki/src/upgrade/v1/Tails/3.6/amd64/test/upgrades.yml.pgp

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