build-deb.yml: Add step names

These get reflected by the web browser interface, enhancing readability.
However, splitting into different steps requires to specify the working
directory.

.forgejo/workflows/build-deb.yml

@@ -5,12 +5,16 @@ jobs:
     container:
       image: forge.a-lec.org/speed-dreams/debian-sd:stable
     steps:
-      - run: |
+      - name: Clone repository
+        run: |
           git clone \
             -b ${{ env.GITHUB_HEAD_REF }} \
             --depth 1 \
             ${{ env.GITHUB_SERVER_URL }}/${{ env.GITHUB_REPOSITORY }}.git \
-          src
+            /src
-        cd src/
+      - name: Configure project
-        cmake -B build -DSD_ASSUME_DATADIR=1
+        working-directory: /src
-        cmake --build build -j$(nproc --all)
+        run: cmake -B build -DSD_ASSUME_DATADIR=1
+      - name: Build project
+        run: cmake --build build -j$(nproc --all)
+        working-directory: /src