Set shell syntax for starship bug-report

It seemed unintuitive that the syntax highlighting
for the config file was set to bash even when it was known
that it was in another language, such as powershell or lua.

src/bug_report.rs

@@ -52,6 +52,15 @@ fn get_pkg_branch_tag() -> &'static str {
 }
 
 fn make_github_issue_link(environment: Environment) -> String {
+    let shell_syntax = match environment.shell_info.name.as_ref() {
+        "powershell" => "pwsh",
+        "fish" => "fish",
+        "cmd" => "lua",
+        // GitHub does not seem to support elvish syntax highlighting.
+        "elvish" => "bash",
+        _ => "bash",
+    };
+
     let body = urlencoding::encode(&format!("#### Current Behavior
 <!-- A clear and concise description of the behavior. -->
 
@@ -76,7 +85,7 @@ fn make_github_issue_link(environment: Environment) -> String {
 - Build Time: {build_time}
 #### Relevant Shell Configuration
 
-```bash
+```{shell_syntax}
 {shell_config}
 ```
 
@@ -100,6 +109,7 @@ fn make_github_issue_link(environment: Environment) -> String {
         rust_channel =  shadow::RUST_CHANNEL,
         build_rust_channel =  shadow::BUILD_RUST_CHANNEL,
         build_time =  shadow::BUILD_TIME,
+        shell_syntax = shell_syntax,
     ))
         .replace("%20", "+");