release: Zephyr 2.7.3

Set version to 2.7.3

Fixes #49354

Signed-off-by: Christopher Friedt <cfriedt@fb.com>
diff --git a/VERSION b/VERSION
index 0879b18..ec52e4b 100644
--- a/VERSION
+++ b/VERSION
@@ -1,5 +1,5 @@
 VERSION_MAJOR = 2
 VERSION_MINOR = 7
-PATCHLEVEL = 2
+PATCHLEVEL = 3
 VERSION_TWEAK = 0
 EXTRAVERSION =