ADD <url> fails if http proxy is used

[r10r]

Proxy environment is setup properly and the following dockerfile builds fine with buildah bud when using buildah v1.33.11.

FROM alpine:latest
RUN env | grep proxy
ADD https://raw.githubusercontent.com/containers/buildah/refs/heads/main/README.md README.md

But after switching to buildah 1.38.0 the file download fails.

STEP 1/3: FROM alpine:latest
STEP 2/3: RUN env | grep proxy
https_proxy=http://proxy.mycompany.de:3128
http_proxy=http://proxy.mycompany.de:3128
STEP 3/3: ADD https://raw.githubusercontent.com/containers/buildah/refs/heads/main/README.md README.md
WARN[0000] Failed, retrying in 1s ... (1/3). Error: Get "https://raw.githubusercontent.com/containers/buildah/refs/heads/main/README.md": dial tcp 185.199.110.133:443: connect: connection refused 
WARN[0002] Failed, retrying in 2s ... (2/3). Error: Get "https://raw.githubusercontent.com/containers/buildah/refs/heads/main/README.md": dial tcp 185.199.110.133:443: connect: connection refused 
WARN[0004] Failed, retrying in 4s ... (3/3). Error: Get "https://raw.githubusercontent.com/containers/buildah/refs/heads/main/README.md": dial tcp 185.199.109.133:443: connect: connection refused