allow whitespaces in data segments

[watson28]

I had an issue with a PEM certificate where the data segments were not separated by breaking lines (\n) but with empty spaces ( ). The library failed to parse the pem file, but OpenSSL didn't complain. Here is an example with the RSA keys used in the unit tests:

~ cat test-cert-rust-pem-rs.pem
-----BEGIN RSA PUBLIC KEY-----
MIIBOgIBAAJBAMIeCnn9G/7g2Z6J+qHOE2XCLLuPoh5NHTO2Fm+PbzBvafBo0oYo QVVy7frzxmOqx6iIZBxTyfAQqBPO3Br59BMCAwEAAQJAX+PjHPuxdqiwF6blTkS0 RFI1MrnzRbCmOkM6tgVO0cd6r5Z4bDGLusH9yjI9iI84gPRjK0AzymXFmBGuREHI sQIhAPKf4pp+Prvutgq2ayygleZChBr1DC4XnnufBNtaswyvAiEAzNGVKgNvzuhk ijoUXIDruJQEGFGvZTsi1D2RehXiT90CIQC4HOQUYKCydB7oWi1SHDokFW2yFyo6 /+lf3fgNjPI6OQIgUPmTFXciXxT1msh3gFLf3qt2Kv8wbr9Ad9SXjULVpGkCIB+g RzHX0lkJl9Stshd/7Gbt65/QYq+v+xvAeT0CoyIg
-----END RSA PUBLIC KEY-----

~ openssl rsa -in test-cert-rust-pem-rs.pem -text -noout
Private-Key: (512 bit, 2 primes)
modulus:
    00:c2:1e:0a:79:fd:1b:fe:e0:d9:9e:89:fa:a1:ce:
    13:65:c2:2c:bb:8f:a2:1e:4d:1d:33:b6:16:6f:8f:
    6f:30:6f:69:f0:68:d2:86:28:41:55:72:ed:fa:f3:
    c6:63:aa:c7:a8:88:64:1c:53:c9:f0:10:a8:13:ce:
    dc:1a:f9:f4:13
publicExponent: 65537 (0x10001) ...

This PR allows the acceptance of white space as separators in the PEM-encoded data.

[jcreekmore]

Based on the code, it looks fine. However, regex apparently bumped since the last time CI ran and requires Rust 1.65 and this crate is still back on 1.60.

If you want to change the Cargo.toml and the workflow to update it to 1.65 (in a follow on commit), I will merge once it passes CI. Otherwise, I will do that tomorrow and will have to get you to rebase your PR.

Scratch that, we don't have an actual dependency on regex. It is apparently pulled in through a test dependency. I want to go back and figure out how to make it so that we don't have to update MSRV.

[jcreekmore]

Works great, thanks.

[jcreekmore]

Released 3.0.3