fix: enable tlsv1.2 if curl supports it (#3464)

curl 7.73 (see curl/curl@aa8777f) changed the output of `curl --help` to display categories, rather than all of the options, unless you pass `--help all`.  This caused the install script to run in a less secure mode.

The install script also calls "wget --help".  "wget --help all" works at least as far back as 1.5.3 (~2015).

Also checked "curl --help all" with curl 7.54.0.  It shows the same output as "curl --help" and returns exit code 0.

CHANGELOG.md

@@ -6,6 +6,11 @@
 
 Previously, `dfx ledger top-up` only accepted canister principals. Now it accepts both principals and canister names.
 
+### fix: installer once again detects if curl supports tlsv1.2
+
+A change to `curl --help` output made it so the install script did not detect
+that the `--proto` and `--tlsv1.2` options are available.
+
 # 0.15.2
 
 ### fix: `dfx canister delete <canister id>` removes the related entry from the canister id store

public/install/200_downloader.sh

@@ -26,7 +26,7 @@ check_help_for() {
     fi
 
     for _arg in "$@"; do
-        if ! "$_cmd" --help | grep -q -- "$_arg"; then
+        if ! "$_cmd" --help all | grep -q -- "$_arg"; then
             _ok="n"
         fi
     done