Update pluggy to 0.7.1 (#3842)

And add a `filterwarnings` entry for new pluggy `DeprecationWarning`.

requirements/dev.txt

@@ -49,9 +49,9 @@ more-itertools==4.2.0 \
     --hash=sha256:a18d870ef2ffca2b8463c0070ad17b5978056f403fb64e3f15fe62a52db21cc0 \
     --hash=sha256:6703844a52d3588f951883005efcf555e49566a48afd4db4e965d69b883980d3 \
     --hash=sha256:2b6b9893337bfd9166bee6a62c2b0c9fe7735dcf85948b387ec8cba30e85d8e8
-pluggy==0.6.0 \
-    --hash=sha256:d345c8fe681115900d6da8d048ba67c25df42973bda370783cd58826442dcd7c \
-    --hash=sha256:e160a7fcf25762bb60efc7e171d4497ff1d8d2d75a3d0df7a21b76821ecbf5c5
+pluggy==0.7.1 \
+    --hash=sha256:6e3836e39f4d36ae72840833db137f7b7d35105079aee6ec4a62d9f80d594dd1 \
+    --hash=sha256:95eb8364a4708392bae89035f45341871286a333f749c3141c20573d2b3876e1
 py==1.5.4 \
     --hash=sha256:e31fb2767eb657cbde86c454f02e99cb846d3cd9d61b318525140214fdc0e98e \
     --hash=sha256:3fd59af7435864e1a243790d322d763925431213b6b8529c6ca71081ace3bbf7

setup.cfg

@@ -48,6 +48,9 @@ filterwarnings =
     ignore:sys.exc_clear\(\) not supported in 3.x; use except clauses:DeprecationWarning
     ignore:classic int division:DeprecationWarning:django.db.backends.base.schema
     ignore:In 3.x, reload\(\) is renamed to imp.reload\(\):DeprecationWarning:django.db.migrations.loader
+    # https://github.com/mozilla/PyPOM/issues/90
+    # (but attributed to pluggy.manager, due to https://github.com/pytest-dev/pluggy/issues/166)
+    ignore:Support for the `implprefix` arg is now deprecated:DeprecationWarning:pluggy.manager
 markers =
     slow: mark a test as slow.
 xfail_strict = true