No merge plz - tweaking semgrep output

Makefile

@@ -187,7 +187,7 @@ safety:  ## Run `safety check` to check python dependencies for vulnerabilities.
 semgrep:
 	@command -v semgrep || (echo "Please run 'pip install -U semgrep'."; exit 1)
 	@echo "███ Running semgrep on securedrop/..."
-	@semgrep --exclude "securedrop/tests/" --error --strict --metrics off --max-chars-per-line 200 --verbose --config "p/r2c-security-audit" securedrop
+	@semgrep --exclude "securedrop/tests/" --error --strict --metrics off --max-chars-per-line=200 --verbose --config "p/r2c-security-audit" securedrop
 	@echo