Change PrologPrinter to write parser Git hash instead of build time

This matches what the B parser's own Prolog term printing code does.

src/main/java/de/tla2b/output/PrologPrinter.java

@@ -60,7 +60,7 @@ public class PrologPrinter {
 
 		// parser version
 		pout.openTerm("parser_version");
-		pout.printAtom(BParser.getBuildRevision());
+		pout.printAtom(BParser.getGitSha());
 		pout.closeTerm();
 		pout.fullstop();