CI: Add fuzz to CRATES

The `fuzz` crate should be included in the `CRATES` variable. In
`run_task` it is only built (not tested) using `cargo --locked build`.

Author: tcharding

contrib/crates.sh

@@ -4,5 +4,5 @@
 # disable verify unused vars, despite the fact that they are used when sourced
 # shellcheck disable=SC2034
 
-# Crates in this workspace to test (excl. fuzz an integration-tests).
-CRATES=(".")                    # Non-workspaces don't have crates.
+# Crates in this workspace to test.
+CRATES=("." "fuzz")