shaka-packager: pin protobuf_29

shaka-packager currently pins abseil-cpp to abseil-cpp_202401 and
overrides protobuf to use the same version of abseil-cpp. 896199fee5bb
("protobuf: 29.3 -> 30.0") switched the default version of protobuf to
protobuf_30. This broke compilation of shaka-packager as protobuf_30 is
incompatible with abseil-cpp_202401 [1]. Fix the build by pinning
protobuf to protobuf_29.

[1]: https://hydra.nixos.org/build/295978700

pkgs/by-name/sh/shaka-packager/package.nix

···
   ninja,
   python3,
   nix-update-script,
-  abseil-cpp,
+  abseil-cpp_202401,
   curl,
   gtest,
   nlohmann_json,
···
   libwebm,
   mbedtls,
   mimalloc,
-  protobuf,
+  protobuf_29,
   zlib,
 }:
 
···
       # pssh_box.py.
       ps.protobuf
     ]))
-    abseil-cpp
+    abseil-cpp_202401
     curl
     gtest
     nlohmann_json
···
     libwebm
     mbedtls
     mimalloc
-    (protobuf.override {
+    (protobuf_29.override {
       # must be the same version as for shaka-packager
-      inherit abseil-cpp;
+      abseil-cpp = abseil-cpp_202401;
     })
     zlib
   ];

pkgs/top-level/all-packages.nix

···
 
   mpvScripts = mpv-unwrapped.scripts;
 
-  shaka-packager = callPackage ../by-name/sh/shaka-packager/package.nix {
-    abseil-cpp = abseil-cpp_202401;
-  };
-
   mu-repo = python3Packages.callPackage ../applications/misc/mu-repo { };
 
   murmur =