deploy: Verify that jazzer.jar is a valid Jazzer jar

Release v0.20.0 failed because the zip containing the Jazzer jar was
passed in instead of the Jazzer jar itself.

deploy/deploy.sh

@@ -33,6 +33,9 @@ JAZZER_COORDINATES=$1
 [ ! -f "${JAZZER_JAR_PATH}" ] && \
   fail "JAZZER_JAR_PATH does not exist at '$JAZZER_JAR_PATH'"
 
+"${JAZZER_JAR_PATH}" --version 2>&1 | grep '^Jazzer v' || \
+  fail "JAZZER_JAR_PATH is not a valid jazzer.jar"
+
 MAVEN_REPO=https://oss.sonatype.org/service/local/staging/deploy/maven2
 
 # The Jazzer jar itself bundles native libraries for multiple architectures and thus can't be built