Update Go version to 1.27 and enable SIMD compilation

This commit updates the project to use Go version 1.27 for all build and testing processes. It also introduces support for experimental SIMD code compilation, enabling it by default while ensuring a portable scalar fallback is available. Documentation has been updated to reflect the new Go version and the use of the experimental SIMD package.

.github/workflows/release.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v5
         with:
-          go-version: "1.26"
+          go-version: "1.27"
       - name: Checkout obitools4 project
         uses: actions/checkout@v5
       - name: Run tests
@@ -54,7 +54,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v5
         with:
-          go-version: "1.26"
+          go-version: "1.27"
 
       - name: Extract version from tag
         id: get_version
@@ -78,7 +78,8 @@ jobs:
             -v "$(pwd):/src" \
             -w /src \
             -e VERSION="${VERSION}" \
-            golang:1.26-alpine \
+            -e GOEXPERIMENT=simd \
+            golang:1.27-alpine \
             sh -c "apk add --no-cache gcc musl-dev zlib-dev zlib-static make && \
                    make LDFLAGS='-linkmode=external -extldflags=-static' obitools"
           mkdir -p artifacts