fix: builder/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123158
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123166
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123178
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123183
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123204

Author: snyk-bot

builder/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:latest
+FROM golang:1.26rc2
 LABEL maintainer="Frederic Boltz <frederic.boltz@gmail.com>"
 
 ENV GOPATH /gopath/