Update build.yml Actions workflow to checkout git submodules

Author: althonos

.github/workflows/build.yml

@@ -25,6 +25,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
+        with:
+            submodules: true
       - name: Build trimal for Linux x86_64
         if: matrix.arch == 'x86_64' && matrix.cpu_instr == 'non_SIMD' 
         run: cmake . -DDISABLE_SSE2=1 -DDISABLE_AVX2=1 && make && file bin/trimal && file bin/readal &&
@@ -67,4 +69,4 @@ jobs:
             apt-get install -q -y cmake make g++ file
           run: |
             cmake . -DDISABLE_SSE2=1 -DDISABLE_AVX2=1 && make && file bin/trimal && file bin/readal &&
-            ./scripts/generate_trimmed_msas.sh && ./scripts/compare_trimmed_msas.sh
+            ./scripts/generate_trimmed_msas.sh && ./scripts/compare_trimmed_msas.sh