fix Rust language frontend not being detected by CLI

README.md

@@ -66,7 +66,7 @@ named arguments:
   -h, --help             show this help message and exit
   -new NEW [NEW ...]     Root-directory with submissions to check for plagiarism (same as the root directory)
   -old OLD [OLD ...]     Root-directory with prior submissions to compare against
-  -l {cpp,csharp,emf,go,java,kotlin,python3,rlang,scala,scheme,swift,text}
+  -l {cpp,csharp,emf,go,java,kotlin,python3,rlang,rust,scala,scheme,swift,text}
                          Select the language to parse the submissions (default: java)
   -bc BC                 Path of  the  directory  containing  the  base  code  (common  framework  used  in  all
                          submissions)

cli/src/test/java/de/jplag/cli/LanguageTest.java

@@ -31,7 +31,7 @@ class LanguageTest extends CommandLineInterfaceTest {
     @Test
     void testLoading() {
         var languages = LanguageLoader.getAllAvailableLanguages();
-        Assertions.assertEquals(12, languages.size(), "Loaded Languages: " + languages.keySet());
+        Assertions.assertEquals(13, languages.size(), "Loaded Languages: " + languages.keySet());
     }
 
     @Test

languages/rust/src/main/java/de/jplag/rust/Language.java

@@ -4,9 +4,15 @@ import java.io.File;
 import java.util.List;
 import java.util.Set;
 
+import org.kohsuke.MetaInfServices;
+
 import de.jplag.ParsingException;
 import de.jplag.Token;
 
+/**
+ * This represents the Rust language as a language supported by JPlag.
+ */
+@MetaInfServices(de.jplag.Language.class)
 public class Language implements de.jplag.Language {
 
     protected static final String[] FILE_EXTENSIONS = {".rs"};