build.sh: build windows/386 and linux/386, update Debian packaging (#193)

* feat(build.sh): build for windows/386

Part of https://github.com/ooni/probe/issues/1315

* fix(build.sh): docker pull so we have latest image

Part of https://github.com/ooni/probe/issues/1315

* fix(build.sh): apk update && apk upgrade to have latest packages

It does not currently seem necessary. But let's be defensive.

Part of https://github.com/ooni/probe/issues/1315.

* fix(windows.yml): for now disable windows/386

It's working locally but not remotely on Windows. We need to
figure out how to install the 386 compiler.

Part of https://github.com/ooni/probe/issues/1315.

* feat(build.sh): build for windows/386

Part of https://github.com/ooni/probe/issues/1315.

* fix(linux.yml): try to enable experimental docker flags

Related to https://github.com/ooni/probe/issues/1315.

See also https://github.com/actions/virtual-environments/issues/368#issuecomment-713588127.

* fix(debian): try to have single workflow with experimental docker

More commits probably needed.

Part of https://github.com/ooni/ooni.org/issues/677.

* remove restriction on the branch name

* maybe we need a pattern also for branches

* less stringent constraints

* consolidated debian workflow into a single workflow

* further fix the debian workflow

* only run debian action for specific branches or tags

* fix(build.sh): package the 386 windows version properly

.github/workflows/windows.yml

@@ -12,7 +12,7 @@ jobs:
         with:
           go-version: "1.14"
       - uses: actions/checkout@v2
-      - run: bash.exe ./build.sh windows
+      - run: bash.exe ./build.sh windows_amd64  # TODO(bassosimone): make windows_386 work
       - run: bash.exe ./smoketest.sh ./CLI/windows/amd64/ooniprobe.exe
       - uses: actions/upload-artifact@v1
         with: