Update git submodules

* Update reno from branch 'master'
  to cd31b907c380635dd8e9c61995a1c0826d4a1137
  - Close files opened by Scanner, Loader
    
    We're seeing noise like the following in doc builds:
    
      /foo/.tox/docs/lib/python3.9/site-packages/docutils/statemachine.py:707:
      ResourceWarning: unclosed file <_io.BufferedReader name='/foo/.git/objects/pack/pack-dd69481843ca1b7377f2f109b0022221437aca20.pack'>
        if not hasattr(pattern, 'match'):
      ResourceWarning: Enable tracemalloc to get the object allocation traceback
    
    Enable tracemalloc for Sphinx gives us the 'Loader' as the root cause:
    
      $ python -W all::ResourceWarning -X tracemalloc=100 -m sphinx.cmd.build ...
      ...
      File "/foo/.tox/docs/lib/python3.9/site-packages/reno/sphinxext.py", lineno 114
        ldr = loader.Loader(conf)
      File "/foo/.tox/docs/lib/python3.9/site-packages/reno/loader.py", lineno 63
        self._load_data()
      ...
    
    (you could also use PYTHONTRACEMALLOC and PYTHONWARNINGS env vars)
    
    Following this thread, it appears 'reno.scanner.Scanner' creates an
    instance of 'dulwich.repo.Repo', however, it fails to close it [1]. The
    'reno.loader.Loader' uses 'Scanner', meaning this also leaves around
    open files.
    
    The solution is simple: add a 'close()' method to both the 'Scanner' and
    'Loader', and provide the necessary '__enter__' and '__exit__' magic
    methods to use it as a context manager, like the 'Repo' object itself
    supports.
    
    [1] https://www.dulwich.io/docs/api/dulwich.repo.html#dulwich.repo.Repo.close
    
    Change-Id: I0b9776f431cf902a9ace5d52961eb77caaae8eaa
    Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

reno

@@ -1 +1 @@
-Subproject commit 8a80087d923d3fb34c3db6d2b70e317716cd92e1
+Subproject commit cd31b907c380635dd8e9c61995a1c0826d4a1137