We cannot compare against origin/main branch because we build from sdist, not git.

--- pipdeptree-2.26.1/tox.toml.orig
+++ pipdeptree-2.26.1/tox.toml
@@ -43,14 +43,6 @@
       "tests",
     ] },
   ],
-  [
-    "diff-cover",
-    "--compare-branch",
-    "{env:DIFF_AGAINST:origin/main}",
-    "{work_dir}{/}coverage.{env_name}.xml",
-    "--fail-under",
-    "100",
-  ],
 ]
 
 [env.fix]
--- pipdeptree-2.26.1/pyproject.toml.orig
+++ pipdeptree-2.26.1/pyproject.toml
@@ -50,7 +50,6 @@
 ]
 optional-dependencies.test = [
   "covdefaults>=2.3",
-  "diff-cover>=9.1.1",
   "pytest>=8.3.2",
   "pytest-console-scripts>=1.4.1",
   "pytest-cov>=5",