Fix Solaris and remove i386 builds

Red Hat all but has dropped support for 32-bit hardware back with
RHEL 8, with many other distros following suit.

We fixed support for Solaris temporarily by removing the dependency of
the final binary on Docker. This occurred as imports previously in a
test-only package landed in a non-test package (despite only being used
in tests), causing the unnecessary import.

See also: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.4_release_notes/deprecated_functionality

Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>

.github/workflows/build.yml

@@ -112,10 +112,8 @@ jobs:
     strategy:
       matrix:
         goos: [freebsd, windows, netbsd, openbsd, solaris]
-        goarch: [386, amd64, arm]
+        goarch: [amd64, arm]
         exclude:
-          - goos: solaris
-            goarch: 386
           - goos: solaris
             goarch: arm
           - goos: windows
@@ -140,7 +138,7 @@ jobs:
     strategy:
       matrix:
         goos: [linux]
-        goarch: [arm, arm64, 386, amd64, riscv64]
+        goarch: [arm, arm64, amd64, riscv64]
       fail-fast: true
     uses: ./.github/workflows/build-vault-ce.yml
     with:
@@ -181,7 +179,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        arch: [arm, arm64, 386, amd64]
+        arch: [arm, arm64, amd64]
     env:
       repo: ${{ github.event.repository.name }}
       version: ${{ needs.product-metadata.outputs.bao-version }}