Parse makefiles as plain text (#1022)

Author: shanman190

src/main/java/org/openrewrite/maven/ConfigurableRewriteMojo.java

@@ -136,6 +136,7 @@ protected Set<String> getPlainTextMasks() {
                 "**/*.ksh",
                 "**/*.lock",
                 "**/lombok.config",
+                "**/[mM]akefile",
                 "**/*.md",
                 "**/*.mf",
                 "**/META-INF/services/**",