chore(deps): update alpine docker tag to v3.21 (#3739)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Dockerfile

@@ -8,7 +8,7 @@ RUN  --mount=type=cache,target=/go/pkg/mod \
      --mount=type=cache,target=/root/.cache/go-build \
      GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o trufflehog .
 
-FROM alpine:3.20
+FROM alpine:3.21
 RUN apk add --no-cache bash git openssh-client ca-certificates rpm2cpio binutils cpio \
     && rm -rf /var/cache/apk/* && update-ca-certificates
 COPY --from=builder /build/trufflehog /usr/bin/trufflehog

Dockerfile.goreleaser

@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 RUN apk add --no-cache bash git openssh-client ca-certificates \
     && rm -rf /var/cache/apk/* && update-ca-certificates