Bump base64 from 0.11.0 to 0.12.3

Bumps [base64](https://github.com/marshallpierce/rust-base64) from 0.11.0 to 0.12.3.
- [Release notes](https://github.com/marshallpierce/rust-base64/releases)
- [Changelog](https://github.com/marshallpierce/rust-base64/blob/master/RELEASE-NOTES.md)
- [Commits](marshallpierce/rust-base64@v0.11.0...v0.12.3)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Cargo.lock

@@ -36,4 +36,4 @@ ansi_term = "0.12"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 libc = "0.2.65"
-base64 = "0.11.0"
+base64 = "0.12.3"