PSS-23488: Update BUILDER_GO version to 1.21.6 for TLS v1.3 (#131)

Dockerfile

@@ -34,6 +34,9 @@ ENV GOEXPERIMENT=${CRYPTO_LIB:+boringcrypto}
 FROM toolchain as builder
 WORKDIR /workspace
 
+ARG CRYPTO_LIB
+ENV GOEXPERIMENT=${CRYPTO_LIB:+boringcrypto}
+
 RUN apk update
 RUN apk add git gcc g++ curl binutils-gold
 
@@ -54,7 +57,7 @@ RUN --mount=type=cache,target=/root/.local/share/golang \
 COPY ./ ./
 
 # Build
-ARG package=.
+ARG package=sigs.k8s.io/cluster-api
 ARG ARCH
 ARG ldflags
 

util/flags/tls_boring.go

@@ -9,5 +9,5 @@ func InsecureSkipVerify(insecureSkipVerify bool) bool {
 }
 
 func GetTlsMaxVersion() uint16 {
-	return tls.VersionTLS12
+	return tls.VersionTLS13
 }