update: upgrade to debian, ca-certificates, wget

docker/Dockerfile

@@ -10,15 +10,15 @@ COPY requirements.txt /requirements.txt
 RUN YARL_NO_EXTENSIONS=1 MULTIDICT_NO_EXTENSIONS=1 pip install --no-cache-dir --prefix=/install -r /requirements.txt
 
 # Load and verify Cosign
-FROM debian:buster-slim as cosign_loader
+FROM debian:bullseye-slim as cosign_loader
 
 SHELL ["/bin/bash", "-c"]
 ARG COSIGN_VERSION
 WORKDIR /go/cosign
 COPY docker/release-cosign.pub /go/cosign/release-cosign.pub
 
 RUN apt-get update \
- && apt-get install -y --no-install-recommends openssl=1.1.\* libssl1.1=1.1.\* ca-certificates=20200601\* wget=1.20.\* \
+ && apt-get install -y --no-install-recommends openssl=1.1.\* libssl1.1=1.1.\* ca-certificates=20210119\* wget=1.21\* \
  && wget -nv https://github.com/sigstore/cosign/releases/download/v${COSIGN_VERSION}/cosign-linux-amd64 \
  && wget -nv https://github.com/sigstore/cosign/releases/download/v${COSIGN_VERSION}/cosign-linux-amd64.sig \
  && openssl dgst -sha256 -verify release-cosign.pub -signature <(base64 -d cosign-linux-amd64.sig) cosign-linux-amd64 \