Revert "Remove unused test data files"

This reverts commit ef24980e667debd0cb8f1f26218c452bacbbe084.
diff --git a/tests/data_files/test-ca-sha256.crt b/tests/data_files/test-ca-sha256.crt
new file mode 100644
index 0000000..9b08fe2
--- /dev/null
+++ b/tests/data_files/test-ca-sha256.crt
@@ -0,0 +1,20 @@
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