Run ldconfig after installing dependencies on CI.

This has previously worked because Pillow wheels were used that had
pre-compiled libraries embedded. But there are no wheels for Python
3.10, and so `ldconfig` needs to be run to properly find these manually
installed libraries.

.github/workflows/build_wheels.yml

@@ -144,15 +144,15 @@ jobs:
           python -m pip install toml
           python build-scripts/environ-from-pyproject.py >> $GITHUB_ENV
 
+      - name: Add /usr/local/lib to dynamic linker path
+        run: echo "/usr/local/lib" | sudo tee /etc/ld.so.conf.d/local-lib.conf
+
       - name: Download QPDF
         run: build-scripts/linux-download-qpdf.bash $QPDF_MIN_VERSION
 
       - name: Build QPDF
         run: build-scripts/linux-build-sdist-deps.bash
 
-      - name: Add LD_LIBRARY_PATH
-        run: echo "LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH" >> $GITHUB_ENV
-
       - name: Build sdist
         run: |
           python -m pip install --upgrade pip

build-scripts/linux-build-sdist-deps.bash

@@ -4,3 +4,5 @@ set -ex
 pushd qpdf
 ./configure --disable-oss-fuzz && make -j && sudo make install
 popd
+
+sudo ldconfig

build-scripts/linux-build-wheel-deps.bash

@@ -19,3 +19,5 @@ if [ ! -f /usr/local/lib/libqpdf.a ]; then
     find /usr/local/lib -name 'libqpdf.so*' -type f -exec strip --strip-debug {} \+
     popd
 fi
+
+ldconfig