Fix reporting of version in prebuilt binaries & docker image

.github/workflows/build.yaml

@@ -31,10 +31,37 @@ env:
   DOCKER_METADATA_ANNOTATIONS_LEVELS: manifest,index
 
 jobs:
+  compute-version:
+    name: Compute version using git describe
+    runs-on: ubuntu-24.04
+    outputs:
+      describe: ${{ steps.git.outputs.describe }}
+      timestamp: ${{ steps.git.outputs.timestamp }}
+    steps:
+      - name: Checkout the code
+        uses: actions/checkout@v4.2.2
+        with:
+          # Need a full clone so that `git describe` reports the right version
+          fetch-depth: 0
+
+      - name: Compute version and timestamp out of git history
+        id: git
+        run: |
+          echo "describe=$(git describe --tags --match 'v*.*.*' --always)" >> $GITHUB_OUTPUT
+          echo "timestamp=$(git log -1 --format=%ct)" >> $GITHUB_OUTPUT
+
+
   build-binaries:
     name: Build binaries
     runs-on: ubuntu-22.04
 
+    needs:
+      - compute-version
+
+    env:
+      VERGEN_GIT_DESCRIBE: ${{ needs.compute-version.outputs.describe }}
+      SOURCE_DATE_EPOCH: ${{ needs.compute-version.outputs.timestamp }}
+
     permissions:
       contents: read
 
@@ -136,6 +163,13 @@ jobs:
       packages: write
       id-token: write
 
+    needs:
+      - compute-version
+
+    env:
+      VERGEN_GIT_DESCRIBE: ${{ needs.compute-version.outputs.describe }}
+      SOURCE_DATE_EPOCH: ${{ needs.compute-version.outputs.timestamp }}
+
     steps:
       - name: Docker meta
         id: meta