use spack.version_info as source of version truth for spack tutorial command (#33860)

* Use spack.spack_version_info as source of truth

Co-authored-by: Todd Gamblin <gamblin2@llnl.gov>

lib/spack/spack/cmd/tutorial.py

@@ -11,6 +11,7 @@
 import llnl.util.tty as tty
 from llnl.util.filesystem import working_dir
 
+import spack
 import spack.cmd.common.arguments as arguments
 import spack.config
 import spack.paths
@@ -24,7 +25,7 @@
 
 
 # tutorial configuration parameters
-tutorial_branch = "releases/v0.18"
+tutorial_branch = "releases/v%s" % ".".join(str(v) for v in spack.spack_version_info[:2])
 tutorial_mirror = "file:///mirror"
 tutorial_key = os.path.join(spack.paths.share_path, "keys", "tutorial.pub")