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

CLI/linux/386/.gitignore

@@ -0,0 +1 @@
+/ooniprobe

CLI/linux/amd64/.gitignore

@@ -1 +1 @@
-*
+/ooniprobe