Revert PyPy envs back to plain pytest

PyPy environments explicitly disable coverage to avoid the significant
runtime overhead it adds. Without coverage data, delta has no accurate
mapping for these envs and falls back to the CPython mapping, causing:
- Unreliable test selection (CPython-mapped tests may fail on PyPy)
- Pre-existing PyPy/min-deps failures surfacing unexpectedly (exit code 1)

Affected envs: pypy3, pypy3-extra-deps, min-pypy3

This follows the same principle as the botocore/mitmproxy fix:
delta is only used where it has accurate coverage mapping.

tox.ini

@@ -248,8 +248,10 @@ setenv =
 [testenv:pypy3]
 basepython = pypy3
 commands =
-    ; not enabling coverage as it significantly increases the run time
-    delta run -- {posargs:--durations=10 scrapy tests}
+    # Not using delta run: coverage is disabled in PyPy envs, so delta has no
+    # accurate mapping and falls back to the CPython mapping, causing unreliable
+    # test selection and surfacing pre-existing PyPy-specific failures.
+    pytest {posargs:--durations=10 scrapy tests}
 
 [testenv:pypy3-extra-deps]
 basepython = pypy3
@@ -286,8 +288,10 @@ passenv =
     DELTA_*
     GITHUB_*
 commands =
-    ; disabling coverage
-    delta run -- {posargs:--durations=10 scrapy tests}
+    # Not using delta run: coverage is disabled in PyPy envs, so delta has no
+    # accurate mapping and falls back to the CPython mapping, causing unreliable
+    # test selection and surfacing pre-existing PyPy/min-deps failures.
+    pytest {posargs:--durations=10 scrapy tests}
 setenv =
     {[min]setenv}