Update to Go 1.18 and push bundled xpkg to Marketplace

[hasheddan]

Description of your changes

Updates to Go 1.18 and builds a bundled xpkg that is pushed to Marketplace.

I have:

• [x] Read and followed Crossplane's contribution process.
• [x] Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Verified local build and added secrets to this repo. Will need to verify successful push after merge.

🤖 (provider-civo) make build
21:41:00 [ .. ] verify go modules dependencies have expected content
all modules verified
21:41:00 [ OK ] go modules dependencies verified
21:41:01 [ .. ] go build linux_amd64
github.com/crossplane-contrib/provider-civo/cmd/provider
21:41:02 [ OK ] go build linux_amd64
21:41:02 [ .. ] docker build build-5d62ce4d/provider-civo-amd64
[+] Building 2.5s (8/8) FINISHED                                                                                                                                                                       
 => [internal] load .dockerignore                                                                                                                                                                 0.0s
 => => transferring context: 2B                                                                                                                                                                   0.0s
 => [internal] load build definition from Dockerfile                                                                                                                                              0.0s
 => => transferring dockerfile: 303B                                                                                                                                                              0.0s
 => [internal] load metadata for gcr.io/distroless/static@sha256:1f580b0a1922c3e54ae15b0758b5747b260bd99d39d40c2edb3e7f6e2452298b                                                                 0.5s
 => [internal] load build context                                                                                                                                                                 0.2s
 => => transferring context: 30.13MB                                                                                                                                                              0.2s
 => CACHED [1/2] FROM gcr.io/distroless/static@sha256:1f580b0a1922c3e54ae15b0758b5747b260bd99d39d40c2edb3e7f6e2452298b                                                                            0.0s
 => => resolve gcr.io/distroless/static@sha256:1f580b0a1922c3e54ae15b0758b5747b260bd99d39d40c2edb3e7f6e2452298b                                                                                   0.0s
 => [2/2] ADD bin/linux_amd64/provider /usr/local/bin/crossplane-civo-provider                                                                                                                    0.1s
 => exporting to oci image format                                                                                                                                                                 1.7s
 => => exporting layers                                                                                                                                                                           1.3s
 => => exporting manifest sha256:cdb4a327e2dc35c20149ec0067d86f1f1947ba684c56f101b104aca909917f76                                                                                                 0.0s
 => => exporting config sha256:546ddf56483cb4c39188950409217e84a94decd410be0f89834922f368f880e8                                                                                                   0.0s
 => => sending tarball                                                                                                                                                                            0.3s
 => importing to docker                                                                                                                                                                           0.2s
21:41:05 [ OK ] docker build build-5d62ce4d/provider-civo-amd64
21:41:05 [ .. ] Building package provider-civo-v0.0.0-50.g0f8f5d3.xpkg for linux_amd64
xpkg saved to /home/dan/code/github.com/crossplane-contrib/provider-civo/_output/xpkg/linux_amd64/provider-civo-v0.0.0-50.g0f8f5d3.xpkg
21:41:07 [ OK ] Built package provider-civo-v0.0.0-50.g0f8f5d3.xpkg for linux_amd64