Use https:// URLs for the bug tracker in the :issue: role.

Thanks to Ezio for noticing this
diff --git a/Doc/tools/pyspecific.py b/Doc/tools/pyspecific.py
index 8f0d090..1699891 100644
--- a/Doc/tools/pyspecific.py
+++ b/Doc/tools/pyspecific.py
@@ -9,7 +9,7 @@
     :license: Python license.
 """
 
-ISSUE_URI = 'http://bugs.python.org/issue%s'
+ISSUE_URI = 'https://bugs.python.org/issue%s'
 SOURCE_URI = 'https://hg.python.org/cpython/file/2.7/%s'
 
 from docutils import nodes, utils