Update mcuboot tag to v1.7.0-rc1

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: I1a5d1f2c5e8dc8afcbe046e4376663e3fc4f94cb
diff --git a/tf-m-build-docs-nightly.yaml b/tf-m-build-docs-nightly.yaml
index 4b2fceb..19eaa37 100644
--- a/tf-m-build-docs-nightly.yaml
+++ b/tf-m-build-docs-nightly.yaml
@@ -56,7 +56,7 @@
           default: 'https://review.trustedfirmware.org/TF-M/trusted-firmware-m'
       - string:
           name: 'MCUBOOT_REFSPEC'
-          default: 'refs/tags/TF-Mv1.2-integ'
+          default: 'refs/tags/1.7.0-rc1'
           description: |
             Specify which MCUboot version to use
             refs/heads/master    : Pick up latest master