pyproject: remove unnecessary extra dependency

pynacl is no longer needed

Author: jku

pyproject.toml

@@ -5,7 +5,7 @@ build-backend = "hatchling.build"
 [project]
 name = "tuf-conformance"
 dependencies = [
-    "securesystemslib[crypto, pynacl]==1.2.0" ,
+    "securesystemslib[crypto]==1.2.0",
     "tuf==5.1.0",
     "pytest==8.3.4"
 ]
@@ -39,4 +39,4 @@ lint.ignore = [
     "ANN101", "ANN102", # nonsense, deprecated in ruff
     "S101",             # assert is fine in pytest tests
     "PLR2004",          # magic values are ok in a test suite
-]
+]