Fix some requires-python regressions (#251)

Fix some regressions from #243

Author: konstin

scenarios/fork/incomplete-markers.toml

@@ -14,6 +14,7 @@ universal = true
 satisfiable = true
 
 [root]
+requires_python = ">=3.9"
 requires = [
   "a==1; python_version < '3.10'",
   "a==2; python_version >= '3.11'",

scenarios/fork/overlapping-markers-basic.toml

@@ -37,6 +37,7 @@ universal = true
 satisfiable = true
 
 [root]
+requires_python = ">=3.9"
 requires = [
   "a>=1.0.0 ; python_version < '3.10'",
   "a>=1.1.0 ; python_version >= '3.10'",

scenarios/tag_and_markers/requires-python-wheels.toml

@@ -9,6 +9,7 @@ requires = ["a==1.0.0"]
 satisfiable = true
 
 [packages.a.versions."1.0.0"]
+requires_python = ">=3.10"
 wheel_tags = ["cp311-cp311-any", "cp310-cp310-any", "cp39-cp39-any"]
 
 [resolver_options]