Support the new location of PipSession

Author: adamtheturtle

pip_check_reqs/common.py

@@ -6,7 +6,11 @@
 import re
 
 from packaging.utils import canonicalize_name
-from pip._internal.download import PipSession
+# Between different versions of pip the location of PipSession has changed.
+try:
+     from pip._internal.network.session import PipSession
+except ImportError:  # pragma: no cover
+    from pip._internal.download import PipSession
 from pip._internal.req.req_file import parse_requirements
 
 log = logging.getLogger(__name__)

pip_check_reqs/find_missing_reqs.py

@@ -6,7 +6,11 @@
 
 from packaging.utils import canonicalize_name
 from pip._internal.commands.show import search_packages_info
-from pip._internal.download import PipSession
+# Between different versions of pip the location of PipSession has changed.
+try:
+     from pip._internal.network.session import PipSession
+except ImportError:  # pragma: no cover
+    from pip._internal.download import PipSession
 from pip._internal.req.req_file import parse_requirements
 from pip._internal.utils.misc import get_installed_distributions