update all dependencies (maven artifacts)

- PDF dependency was missing in the pom file the JDK8
  * We should think about creating a parent pom - in that case all plantuml dependencies could be in the parent pom and we would only the mantain one pom file.
    (It is also possible to drop the Java 8 support.)
  * Why do we not have any PDF tests?
- add rule to ignore version update hint with `-dev` followed by a dot and date (e.g. `0.37.0-dev.20230308`)
- migration from JUnit4 to JUnit5

src/test/java/net/sourceforge/plantuml/servlet/TestAsciiCoder.java

@@ -6,6 +6,9 @@ import java.net.HttpURLConnection;
 import java.net.URL;
 import java.net.URLConnection;
 
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
 import net.sourceforge.plantuml.servlet.utils.TestUtils;
 import net.sourceforge.plantuml.servlet.utils.WebappTestCase;
 
@@ -15,24 +18,26 @@ public class TestAsciiCoder extends WebappTestCase {
     /**
      * Verifies the decoding for the Bob -> Alice sample
      */
+    @Test
     public void testBobAliceSampleDiagramDecoding() throws IOException {
         final URL url = new URL(getServerUrl() + "/coder/" + TestUtils.SEQBOB);
         final URLConnection conn = url.openConnection();
         // Analyze response
         // Verifies the Content-Type header
-        assertEquals(
-            "Response content type is not TEXT PLAIN or UTF-8",
+        Assertions.assertEquals(
             "text/plain;charset=utf-8",
-            conn.getContentType().toLowerCase()
+            conn.getContentType().toLowerCase(),
+            "Response content type is not TEXT PLAIN or UTF-8"
         );
         // Get and verify the content
         final String diagram = getContentText(conn);
-        assertEquals(TestUtils.SEQBOBCODE, diagram);
+        Assertions.assertEquals(TestUtils.SEQBOBCODE, diagram);
     }
 
     /**
      * Verifies the encoding for the Bob -> Alice sample
      */
+    @Test
     public void testBobAliceSampleDiagramEncoding() throws IOException {
         final URL url = new URL(getServerUrl() + "/coder");
         final HttpURLConnection conn = (HttpURLConnection)url.openConnection();
@@ -45,20 +50,16 @@ public class TestAsciiCoder extends WebappTestCase {
         }
         // Analyze response
         // HTTP response 200
-        assertEquals(
-            "Bad HTTP status received",
-            200,
-            conn.getResponseCode()
-        );
+        Assertions.assertEquals(200, conn.getResponseCode(), "Bad HTTP status received");
         // Verifies the Content-Type header
-        assertEquals(
-            "Response content type is not TEXT PLAIN or UTF-8",
+        Assertions.assertEquals(
             "text/plain;charset=utf-8",
-            conn.getContentType().toLowerCase()
+            conn.getContentType().toLowerCase(),
+            "Response content type is not TEXT PLAIN or UTF-8"
         );
         // Get the content and verify its size
         final String diagram = getContentText(conn.getInputStream());
-        assertEquals(TestUtils.SEQBOB, diagram);
+        Assertions.assertEquals(TestUtils.SEQBOB, diagram);
     }
 
 }