Skip mypy on PyPy to avoid librt compilation issues (#1086)

* Skip mypy on PyPy to avoid librt compilation issues

mypy's mypyc-compiled dependencies (librt) use CPython internal
structures that don't exist in PyPy, causing compilation failures.

Fixes test environment installation on PyPy.

* Fix CI: unset HATCH_ENV for check_release, use direct version-cmd

Two issues:
1. Global HATCH_ENV=cov caused 'hatch version' to fail with
   'Environment cov is not a builder environment' in check_release

2. Added explicit version-cmd to .jupyter-releaser.toml for robustness

* Remove version-cmd, use default hatch version

version-cmd is for bumping, not reading. With HATCH_ENV unset,
hatch version works correctly for both reading and bumping.

Author: rgbkrk

.github/workflows/main.yml

@@ -19,6 +19,8 @@ env:
 jobs:
   check_release:
     runs-on: ubuntu-latest
+    env:
+      HATCH_ENV: ""
     steps:
       - uses: actions/checkout@v4
       - uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1

pyproject.toml

@@ -48,7 +48,7 @@ test = [
     "anyio",
     "coverage",
     "ipykernel>=6.14",
-    "mypy",
+    "mypy; platform_python_implementation != 'PyPy'",
     "paramiko; sys_platform == 'win32'",
     "pre-commit",
     "pytest",