spdk: update submodule to more recent upstream

This commit fast-forwards the SPDK submodule to upstream commit
93bd60e0de6b161567182d965239735bf467e85c to enable the py3-only build.
(Without said commit, SPDK configure script fails to find the python
interpreter in py3-only environment.)

Signed-off-by: Nathan Cutler <ncutler@suse.com>

diff --git a/src/spdk b/src/spdk
index b17d4d91359078a00ec60e6016b8c5c9c6b41a91..93bd60e0de6b161567182d965239735bf467e85c 160000 (submodule)
--- a/src/spdk
+++ b/src/spdk
@@ -1 +1 @@
-Subproject commit b17d4d91359078a00ec60e6016b8c5c9c6b41a91
+Subproject commit 93bd60e0de6b161567182d965239735bf467e85c