Preparing for release v1.15.0

[nebeid]

Description of changes:

Bump minor version number to prepare for the release.

List of changes to be included:

What's Changed

• Add EVP_MD_do_all by @WillChilds-Klein in Add EVP_MD_do_all #1154
• error: '%s' directive argument is null by @justsmth in error: '%s' directive argument is null #1158
• Fix build on gcc 4.8.3 by @samuel40791765 in Fix build on gcc 4.8.3 #1156
• Remove duplicate handling of OPENSSL_NO_ASM from CMake. by @PiotrSikora in Remove duplicate handling of OPENSSL_NO_ASM from CMake. #1149
• Add -DBUILD_TOOL=OFF to CMake. by @PiotrSikora in Add -DBUILD_TOOL=OFF to CMake. #1148
• Upstream merge 2023 08 09 by @justsmth in Upstream merge 2023 08 09 #1152, Revert "Upstream merge 2023 08 09 (#1152)" #1160, Recreating: Upstream merge 2023 08 09 #1161
• Add missing symbols for SSLProxy support by @samuel40791765 in add missing symbols for SSLProxy support #1155
• Update montgomery multiplication to use s2n-bignum's verified scalar bignum functions by @aqjune-aws in Update montgomery multiplication to use s2n-bignum's verified scalar bignum functions #1135
• Add more ssl runner tests for multiple certificate support by @samuel40791765 in Add more ssl runner tests for multiple certificate support #1141
• CVE-2023-3446 and CVE-2023-3817 by @dkostic in CVE-2023-3446 and CVE-2023-3817 #1163
• Minor fix in aead test by @dkostic in Minor fix in aead test #1165
• Conditionally enable Neon version of s2n-bignum implementations for montgomery multiplications by @aqjune-aws in Conditionally enable Neon version of s2n-bignum implementations for montgomery multiplications #1164
• Fix build for ppc64le by @justsmth in Fix build for ppc64le #1167
• add additional documentation for X509 headers by @samuel40791765 in add additional documentation for X509 headers #1142

New Contributors

• @PiotrSikora made their first contribution in Remove duplicate handling of OPENSSL_NO_ASM from CMake. #1149

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.