gnu: taskwarrior: Update to 3.4.2.

* gnu/packages/task-management.scm (taskwarrior): Update to 3.4.2.
[source]: Update to new release location.  Add patch for proper SQLite
linking.  Add snippet to remove sourceless PDF.
[native-inputs]: Add dependencies for Rust code.
[inputs]: Add sqlite-next.
[arguments] <#:phases>: Adjust for Rust dependency build.
* gnu/packages/rust-crates.scm (lookup-cargo-inputs): Add entry for
taskwarrior.
* gnu/packages/patches/task-link-taskchampion-cpp-with-sqlite3.patch:
New file.
* gnu/local.mk (dist_patch_DATA): Register it.

Change-Id: Ica26c93347dedcba83a473cb60b176cf1195a806
Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/patches/taskwarrior-link-taskchampion-cpp-with-sqlite3.patch

@@ -0,0 +1,19 @@
+From: Gordon Ball <gordon@chronitis.net>
+Date: Fri, 19 Dec 2025 20:59:08 +0100
+Subject: link taskchampion-cpp with sqlite3
+
+Since the rusqlite dependency has been rewritten not to use bundled sqlite, we need to explicitly link sqlite3 at build time.
+---
+ src/taskchampion-cpp/CMakeLists.txt | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/src/taskchampion-cpp/CMakeLists.txt b/src/taskchampion-cpp/CMakeLists.txt
+index 9584670..22bcfa0 100644
+--- a/src/taskchampion-cpp/CMakeLists.txt
++++ b/src/taskchampion-cpp/CMakeLists.txt
+@@ -69,3 +69,5 @@ corrosion_add_cxxbridge(taskchampion-cpp
+   CRATE taskchampion_lib
+   FILES lib.rs
+ )
++
++corrosion_link_libraries(taskchampion_lib sqlite3)