Configure fails with >= botan 3.0.0

[orbea]

OS: Gentoo
SoftHSMv2: f4661af
Botan: 3.0.0

When trying to build with botan using --with-crypto-backend=botan configure will fail.

checking for botan-2 >= 2.5.0... no
configure: error: Cannot find Botan

Looking at config.log shows:

configure:6975: checking for botan-2 >= 2.5.0
configure:6982: $PKG_CONFIG --exists --print-errors "botan-2 >= 2.5.0"
Package botan-2 was not found in the pkg-config search path.
Perhaps you should add the directory containing `botan-2.pc'
to the PKG_CONFIG_PATH environment variable
Package 'botan-2', required by 'virtual:world', not found
configure:6985: $? = 1
configure:6999: $PKG_CONFIG --exists --print-errors "botan-2 >= 2.5.0"
Package botan-2 was not found in the pkg-config search path.
Perhaps you should add the directory containing `botan-2.pc'
to the PKG_CONFIG_PATH environment variable
Package 'botan-2', required by 'virtual:world', not found
configure:7002: $? = 1
configure:7016: result: no
Package 'botan-2', required by 'virtual:world', not found
configure:7033: error: Cannot find Botan

Where it is checking for the botan-2.pc pkgconfig file, but with botam-3.0.0 I have a botan-3.pc pkgconfig file.