Bump ktfmt from 0.37 to 0.39

Bumps [ktfmt](https://github.com/facebookincubator/ktfmt) from 0.37 to 0.39.
- [Release notes](https://github.com/facebookincubator/ktfmt/releases)
- [Commits](facebook/ktfmt@v0.37...v0.39)

---
updated-dependencies:
- dependency-name: com.facebook:ktfmt
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

lib/build.gradle

@@ -36,7 +36,7 @@ dependencies {
 
 	palantirJavaFormatCompileOnly 'com.palantir.javaformat:palantir-java-format:1.1.0'
 
-	String VER_KTFMT = '0.37'
+	String VER_KTFMT = '0.39'
 	ktfmtCompileOnly "com.facebook:ktfmt:$VER_KTFMT"
 	String VER_KTLINT_GOOGLE_JAVA_FORMAT = '1.7' // for JDK 8 compatibility
 	ktfmtCompileOnly("com.google.googlejavaformat:google-java-format") {