Fix failing unit tests in GitHub Actions matrix

- Clojure: Use 'clojure' instead of 'clj -M' for standalone script
- Dart: Add proper pubspec.yaml with SDK environment constraint
- Julia: Install SHA package before running tests
- Lua: Use lua5.4 explicitly, add awk for portable HMAC output parsing
- Perl: Install libjson-perl and libwww-perl dependencies
- Bash: Make un.sh executable before test
- OCaml: Add str.cma and unix.cma for Str module support
- OCaml unit test: Remove Str dependency with pure string search

tests/unit/test_lua.lua

@@ -115,7 +115,8 @@ end)
 print("\n=== HMAC Signature Tests ===")
 
 local function hmac_sha256(secret, message)
-    local cmd = string.format("echo -n '%s' | openssl dgst -sha256 -hmac '%s' 2>/dev/null | sed 's/^.* //'",
+    -- Use printf for better portability and awk to extract just the hash
+    local cmd = string.format("printf '%%s' '%s' | openssl dgst -sha256 -hmac '%s' | awk '{print $NF}'",
         message:gsub("'", "'\\''"), secret:gsub("'", "'\\''"))
     local handle = io.popen(cmd)
     if handle then