Expect publish output to be shared through a file (#678)

* Expect publish output to be shared through a file

* throw at all times

* match latest changes

* fmt

* rename things

* update changesets

* add changeset

Author: Andarist

.changeset/shy-months-crash.md

@@ -0,0 +1,5 @@
+---
+"@changesets/action": minor
+---
+
+Published packages detection done through stdout parsing was replaced with one based on the shared output file using `CHANGESETS_OUTPUT` environment variable. When using custom scripts this environment variable should always be passed down to the Changesets CLI invocations.

package.json

@@ -21,11 +21,11 @@
     "@actions/core": "^3.0.1",
     "@actions/exec": "^3.0.0",
     "@actions/github": "^9.1.1",
-    "@changesets/get-release-plan": "^5.0.0-next.6",
+    "@changesets/get-release-plan": "^5.0.0-next.7",
     "@changesets/ghcommit": "^3.0.0-next.1",
-    "@changesets/git": "^4.0.0-next.5",
-    "@changesets/pre": "^3.0.0-next.5",
-    "@changesets/read": "^1.0.0-next.6",
+    "@changesets/git": "^4.0.0-next.6",
+    "@changesets/pre": "^3.0.0-next.6",
+    "@changesets/read": "^1.0.0-next.7",
     "@manypkg/get-packages": "^3.1.0",
     "@octokit/core": "^7.0.6",
     "@octokit/plugin-throttling": "^11.0.3",
@@ -35,10 +35,10 @@
     "tinyexec": "^1.2.4"
   },
   "devDependencies": {
-    "@changesets/changelog-github": "^1.0.0-next.5",
-    "@changesets/cli": "^3.0.0-next.6",
-    "@changesets/types": "^7.0.0-next.5",
-    "@changesets/write": "^1.0.0-next.5",
+    "@changesets/changelog-github": "^1.0.0-next.6",
+    "@changesets/cli": "^3.0.0-next.7",
+    "@changesets/types": "^7.0.0-next.6",
+    "@changesets/write": "^1.0.0-next.6",
     "@tsconfig/node24": "^24.0.4",
     "@types/node": "^24.12.4",
     "@types/semver": "^7.7.1",