release: Zephyr 2.7.0-rc1

Set version to 2.7.0-rc1

Signed-off-by: Christopher Friedt <chrisfriedt@gmail.com>
diff --git a/VERSION b/VERSION
index 808984a..2bedb4e 100644
--- a/VERSION
+++ b/VERSION
@@ -1,5 +1,5 @@
 VERSION_MAJOR = 2
-VERSION_MINOR = 6
-PATCHLEVEL = 99
+VERSION_MINOR = 7
+PATCHLEVEL = 0
 VERSION_TWEAK = 0
-EXTRAVERSION =
+EXTRAVERSION = rc1