Update ICU to v71.1

This is so that LOOT can be packaged as a Flatpack package that uses the
KDE runtime's ICU libraries, which are v71.1, and so avoid bundling
a different version.

.github/workflows/ci.yml

@@ -42,6 +42,14 @@ jobs:
           wget https://boostorg.jfrog.io/artifactory/main/release//1.81.0/source/boost_1_81_0.tar.gz
           tar -xf boost_1_81_0.tar.gz
 
+      - name: Get ICU
+        id: get-icu
+        run: |
+          wget https://github.com/unicode-org/icu/releases/download/release-71-1/icu4c-71_1-Ubuntu20.04-x64.tgz
+          tar -xf icu4c-71_1-Ubuntu20.04-x64.tgz
+
+          echo "root=${{ github.workspace }}/icu/usr/local" >> $GITHUB_OUTPUT
+
       - name: Install APT package dependencies
         run: |
           sudo apt-get update
@@ -58,7 +66,7 @@ jobs:
           mkdir build
           cd build
           export CXX="g++-10" CC="gcc-10"
-          cmake .. -DBOOST_ROOT="boost_1_81_0" -DCPACK_PACKAGE_VERSION="${{ steps.get-libloot-version.outputs.version }}"
+          cmake .. -DBOOST_ROOT="boost_1_81_0" -DICU_ROOT="${{ steps.get-icu.outputs.root }}" -DCPACK_PACKAGE_VERSION="${{ steps.get-libloot-version.outputs.version }}"
           make all
 
       - name: Run tests

CMakeLists.txt

@@ -61,7 +61,7 @@ endif()
 find_package(Boost REQUIRED)
 
 if(NOT CMAKE_SYSTEM_NAME STREQUAL "Windows")
-    find_package(ICU REQUIRED COMPONENTS uc)
+    find_package(ICU 71.1 EXACT REQUIRED COMPONENTS data uc)
     find_package(TBB REQUIRED)
 endif()
 
@@ -447,11 +447,11 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
     target_link_libraries(loot PRIVATE ${LOOT_LIBS})
     target_link_libraries(libloot_tests PRIVATE ${LOOT_LIBS})
 else()
-    set(LOOT_LIBS ICU::uc pthread stdc++fs TBB::tbb)
+    set(LOOT_LIBS ICU::data ICU::uc pthread stdc++fs TBB::tbb)
 
     target_link_libraries(libloot_internals_tests PRIVATE ${LOOT_LIBS})
     target_link_libraries(loot PRIVATE ${LOOT_LIBS})
-    target_link_libraries(libloot_tests PRIVATE pthread)
+    target_link_libraries(libloot_tests PRIVATE ${LOOT_LIBS})
 endif()
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")