Run the echo fuzzer in the CI

.github/workflows/fuzzing.yml

@@ -42,6 +42,7 @@ jobs:
           - { name: fuzz_date, should_pass: false }
           - { name: fuzz_expr, should_pass: true }
           - { name: fuzz_printf, should_pass: false }
+          - { name: fuzz_echo, should_pass: false }
           - { name: fuzz_parse_glob, should_pass: true }
           - { name: fuzz_parse_size, should_pass: true }
           - { name: fuzz_parse_time, should_pass: true }