configure: Bump the minimum required Python version to 3.6

All our supported build platforms have Python 3.6 or newer nowadays, and
there are some useful features in Python 3.6 which are not available in
3.5 yet (e.g. the type hint annotations which will allow us to statically
type the QAPI parser), so let's bump the minimum Python version to 3.6 now.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200923162908.95372-1-thuth@redhat.com>
Message-Id: <20200925154027.12672-16-alex.bennee@linaro.org>
diff --git a/docs/conf.py b/docs/conf.py
index 606f623..00e1b75 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -36,9 +36,9 @@
 # In newer versions of Sphinx this will display nicely; in older versions
 # Sphinx will also produce a Python backtrace but at least the information
 # gets printed...
-if sys.version_info < (3,5):
+if sys.version_info < (3,6):
     raise ConfigError(
-        "QEMU requires a Sphinx that uses Python 3.5 or better\n")
+        "QEMU requires a Sphinx that uses Python 3.6 or better\n")
 
 # The per-manual conf.py will set qemu_docdir for a single-manual build;
 # otherwise set it here if this is an entire-manual-set build.