build: recommend Xcode 13 or later

Change-Id: Ic2c323adade7947326ed7a6cf40a4525ad084987
diff --git a/.waf-tools/default-compiler-flags.py b/.waf-tools/default-compiler-flags.py
index 98b3a7f..8bbc29a 100644
--- a/.waf-tools/default-compiler-flags.py
+++ b/.waf-tools/default-compiler-flags.py
@@ -27,9 +27,9 @@
         if Utils.unversioned_sys_platform() == 'darwin':
             if ccver < (10, 0, 0):
                 errmsg = ('The version of Xcode you are using is too old.\n'
-                          'The minimum supported Xcode version is 12.4.')
-            elif ccver < (12, 0, 0):
-                warnmsg = ('Using a version of Xcode older than 12.4 is not '
+                          'The minimum supported Xcode version is 13.0.')
+            elif ccver < (13, 0, 0):
+                warnmsg = ('Using a version of Xcode older than 13.0 is not '
                            'officially supported and may result in build failures.')
         elif ccver < (7, 0, 0):
             errmsg = ('The version of clang you are using is too old.\n'
diff --git a/Dockerfile b/Dockerfile
index 9d9de95..92bc364 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -54,7 +54,8 @@
 COPY --link --from=build /etc/ndn/nlsr.conf.sample /config/nlsr.conf
 
 RUN --mount=from=build,source=/deps,target=/deps \
-    apt-get install -Uy --no-install-recommends $(cat /deps/nlsr) \
+    apt-get install -Uy --no-install-recommends \
+        $(cat /deps/nlsr) \
     && apt-get distclean
 
 ENV HOME=/config