[libpeas] Bump to 0.21.0

[Garrett Regier <gregier src gnome org>]

commit b74fd58972a99771d7cb3a1f19526a885f88a114
Author: Garrett Regier <garrettregier gmail com>
Date:   Fri Mar 24 21:24:38 2017 -0700

    Bump to 0.21.0

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index b6af16a..2b188c1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -17,7 +17,7 @@ AC_PREREQ(2.63.2)
 # <mclasen> on the stable branch, interface age == micro
 # <mclasen> on the unstable (ie master), interface age = 0
 m4_define(peas_major_version,  1)
-m4_define(peas_minor_version,  20)
+m4_define(peas_minor_version,  21)
 m4_define(peas_micro_version,  0)
 m4_define(peas_interface_age,  0)