Use checksums for external linting tools

* This updates detekt to 1.16.0 (from 1.1.1), and updates where it loads
  it from
* This checks the sha256 hash of the file against known correct values.
* This does NOT update ktlint. Newer ktlint versions expect globs, not
  absolute file paths, so it breaks on our list of absolute file paths.

Makefile

@@ -67,6 +67,8 @@ install: clean ## install the package to the active Python's site-packages
 	python setup.py install
 
 install-kotlin-linters: ## install ktlint and detekt for linting Kotlin output
-	curl -sSLO https://github.com/shyiko/ktlint/releases/download/0.29.0/ktlint
+	test -f ktlint || curl -sSLO https://github.com/shyiko/ktlint/releases/download/0.29.0/ktlint
+	echo "03c9f9f78f80bcdb44c292d95e4d9abf221daf5e377673c1b6675a8003eab94d *ktlint" | sha256sum -c -
 	chmod a+x ktlint
-	curl -sSL --output "detekt-cli-1.1.1-all.jar" https://bintray.com/arturbosch/code-analysis/download_file?file_path=io%2Fgitlab%2Farturbosch%2Fdetekt%2Fdetekt-cli%2F1.1.1%2Fdetekt-cli-1.1.1-all.jar
+	test -f detekt-cli.jar || curl -sSL --output "detekt-cli.jar" https://github.com/detekt/detekt/releases/download/v1.16.0/detekt-cli-1.16.0-all.jar
+	echo "dd63aae60cce4b0516ffc11d31b6280d4010ab481754c7e49b2c9e78db877ca4 *detekt-cli.jar" | sha256sum -c -

tests/test_kotlin.py

@@ -17,13 +17,8 @@
 ROOT = Path(__file__).parent
 
 
-# The version of Detekt built. Must match the version checked out in
-# Makefile
-DETEKT_VERSION = "1.1.1"
-
-
 def run_detekt(files):
-    detekt_exec = ROOT.parent / f"detekt-cli-{DETEKT_VERSION}-all.jar"
+    detekt_exec = ROOT.parent / "detekt-cli.jar"
     # We want to make sure this runs on CI, but it's not required
     # for local development
     if detekt_exec.is_file() or "CI" in os.environ: