update go and docker-compose builder pins

Dockerfile.riscv64

@@ -23,7 +23,7 @@
 # -----------------------------------------------------------------------------
 # Alpine edge has docker-cli for riscv64 but NOT docker-compose.
 # Build it from source since Go has excellent riscv64 cross-compilation.
-FROM --platform=$BUILDPLATFORM golang:1.25.9-alpine AS compose-builder
+FROM --platform=$BUILDPLATFORM golang:1.26.8-alpine AS compose-builder
 ARG TARGETARCH
 
 RUN apk add --no-cache git
@@ -72,7 +72,7 @@ RUN MAKEFLAGS="-j$(nproc)" npm ci --omit=dev --ignore-scripts \
 # -----------------------------------------------------------------------------
 # Stage 4: Go Collector Builder (cross-compile from build platform)
 # -----------------------------------------------------------------------------
-FROM --platform=$BUILDPLATFORM golang:1.25.13 AS go-builder
+FROM --platform=$BUILDPLATFORM golang:1.26.8 AS go-builder
 ARG TARGETARCH
 WORKDIR /app
 COPY collector/ ./collector/