fix: use dynamic arch for opentofu binary downloads (#122)

Containerfile.multiarch

@@ -26,7 +26,7 @@ ENV TOFU_VERSION="${TOFU_VERSION:-v1.8.6}"
 
 RUN apk --update add --virtual .build-deps libarchive-tools && \
     apk add --no-cache curl git openssh-client && \
-    curl -SsfL "https://github.com/opentofu/opentofu/releases/download/${TOFU_VERSION}/tofu_${TOFU_VERSION##v}_linux_amd64.zip" | \
+    curl -SsfL "https://github.com/opentofu/opentofu/releases/download/${TOFU_VERSION}/tofu_${TOFU_VERSION##v}_linux_${TARGETARCH}.zip" | \
         bsdtar -xf - -C /usr/local/bin tofu && \
     chmod 755 /usr/local/bin/tofu && \
     apk del .build-deps && \

plugin/utils.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	"github.com/Masterminds/semver/v3"
@@ -24,9 +25,10 @@ func installPackage(ctx context.Context, client *http.Client, version string, ma
 	}
 
 	packageURL := fmt.Sprintf(
-		"https://github.com/opentofu/opentofu/releases/download/v%s/tofu_%s_linux_amd64.zip",
+		"https://github.com/opentofu/opentofu/releases/download/v%s/tofu_%s_linux_%s.zip",
 		semverVersion.String(),
 		semverVersion.String(),
+		runtime.GOARCH,
 	)
 
 	tmpdir, err := os.MkdirTemp("/tmp", "tofu_dl_")