Add changelog entry

changelog.d/pr-10273

@@ -0,0 +1,22 @@
+synopsis: Show why `cabal act-as-setup configure` failed
+packages: Cabal
+prs: #10273
+significance:
+
+description: {
+
+When `cabal act-as-setup configure` fails, it prints a list of "missing or
+private dependencies".
+
+Now, it will show you if each failing dependency is missing, private, or an
+incompatible version:
+
+```
+Error: [Cabal-8010]
+Encountered missing or private dependencies:
+    Lib:{bar-internal,foo-internal} (missing :bar-internal),
+    base <=1.0 (installed: 4.18.2.1),
+    package-that-does-not-exist (missing)
+```
+
+}