fix issuer of OTP URI should be URI-encoded. (#6634)
fix issuer of OTP URI should be URI-encoded. (#6634)

* fix: Issuer of OTP URI should be URI-encoded.

follow this link https://github.com/google/google-authenticator/wiki/Key-Uri-Format .

* filter unsafe character ':' in issuer

* Use Replace rather than ReplaceAll

vCaesar/gitea,kubatyszko/gitea,sapk-fork/gitea,cez81/gitea,kubatyszko/gitea,cez81/gitea,typeless/gitea,kubatyszko/gitea,go-gitea/gitea,go-gitea/gitea,go-gitea/gitea,typeless/gitea,sapk-fork/gitea,sapk-fork/gitea,vdbt/gitea,lafriks/gitea,lafriks/gitea,vCaesar/gitea,typeless/gitea,cez81/gitea,vdbt/gitea,lafriks/gitea,typeless/gitea,sapk-fork/gitea