Added an arm64 image for coil

[bells17]

Added an arm64 image for the coil.

• https://github.com/cybozu-go/coil/issues/196

[bells17]

@Hsn723 Hi, I modified to use a quay.io/cybozu/ubuntu image that supports multi-architecture. Would you review this PR again?

[terassyi]

We are sorry to keep you waiting. I added some comments. Please check it. Thank you.

[bells17]

@terassyi Thank you for your review. I fixed the point that you commented on. Would you review this again?

[bells17]

@terassyi Sorry, I fixed the point that you commented on.

[terassyi]

@bells17 Thank you for your contribution! LGTM.