package/libnss: security bump to version 3.73

Fixes the following security issue:

- CVE-2021-43527: Heap overflow in NSS when verifying DSA/RSA-PSS
  DER-encoded signatures

For more details, see the advisory:
https://www.mozilla.org/en-US/security/advisories/mfsa2021-51/

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Reviewed-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libnss/libnss.hash

@@ -1,4 +1,4 @@
-# From https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_72_RTM/src/SHA256SUMS
-sha256  6ea60a9ff113e493ea2ab25f41ea75a9fbd10af7903f26f703dac8680732d02e  nss-3.72.tar.gz
+# From https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_73_RTM/src/SHA256SUMS
+sha256  566d3a68da9b10d7da9ef84eb4fe182f8f04e20d85c55d1bf360bb2c0096d8e5  nss-3.73.tar.gz
 # Locally calculated
 sha256  a20c1a32d1f8102432360b42e932869f7c11c7cdbacf9cac554c422132af47f4  nss/COPYING

package/libnss/libnss.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBNSS_VERSION = 3.72
+LIBNSS_VERSION = 3.73
 LIBNSS_SOURCE = nss-$(LIBNSS_VERSION).tar.gz
 LIBNSS_SITE = https://ftp.mozilla.org/pub/mozilla.org/security/nss/releases/NSS_$(subst .,_,$(LIBNSS_VERSION))_RTM/src
 LIBNSS_DISTDIR = dist