improve test template

Some test descriptions have commas and other shenanigans in them.
`slugify` solves all those problems with one filter.

Author: senekor

exercises/practice/acronym/.meta/test_template.tera

@@ -3,7 +3,7 @@
 {% if loop.index != 1 -%}
 #[ignore]
 {% endif -%}
-fn {{ test.description | lower | replace(from=" ", to="_") }}() {
+fn {{ test.description | slugify | replace(from="-", to="_") }}() {
     let input = {{ test.input.phrase | json_encode() }};
     let output = {{ crate_name }}::{{ fn_names[0] }}(input);
     let expected = {{ test.expected | json_encode() }};

rust-tooling/src/default_test_template.tera

@@ -3,7 +3,7 @@
 {% if loop.index != 1 -%}
 #[ignore]
 {% endif -%}
-fn {{ test.description | lower | replace(from=" ", to="_") }}() {
+fn {{ test.description | slugify | replace(from="-", to="_") }}() {
     let input = {{ test.input | json_encode() }};
     let output = {{ crate_name }}::{{ fn_names[0] }}(input);
     let expected = {{ test.expected | json_encode() }};