build.yml: Add step identifiers

These get reflected by the web browser interface, enhancing readability.

.forgejo/workflows/build.yml

@@ -5,12 +5,15 @@ jobs:
     container:
       image: forge.a-lec.org/speed-dreams/debian-sd:stable
     steps:
-      - run: |
+      - id: Clone repository
+        run: |
         git clone \
           -b ${{ env.GITHUB_HEAD_REF }} \
           --depth 1 \
           ${{ env.GITHUB_SERVER_URL }}/${{ env.GITHUB_REPOSITORY }}.git \
           src
         cd src/
-        cmake -B build -DSD_ASSUME_DATADIR=1
-        cmake --build build -j$(nproc --all)
+      - id: Configure project
+        run: cmake -B build -DSD_ASSUME_DATADIR=1
+      - id: Build project
+        run: cmake --build build -j$(nproc --all)