giphy: Don't change logo color in night mode.
giphy: Don't change logo color in night mode.

Since giphy logo is no longer an svg, we don't need to change its
color.

eeshangarg/zulip,andersk/zulip,andersk/zulip,punchagan/zulip,punchagan/zulip,eeshangarg/zulip,hackerkid/zulip,hackerkid/zulip,rht/zulip,rht/zulip,kou/zulip,kou/zulip,punchagan/zulip,zulip/zulip,zulip/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,punchagan/zulip,punchagan/zulip,zulip/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,rht/zulip,andersk/zulip,kou/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,zulip/zulip,kou/zulip,rht/zulip,andersk/zulip,punchagan/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,hackerkid/zulip,hackerkid/zulip,zulip/zulip,hackerkid/zulip